literature review search string

Writing your thesis and conducting a literature review

Writing your thesis
Your literature review
Defining a research question
Choosing where to search

Search strings

Limiters and filters
Developing inclusion/exclusion criteria
Managing your search results
Screening, evaluating and recording
Snowballing and grey literature
Further information and resources

The next step is to create your search strings. Each search string will represent a theme/concept of your research. Search strings are a combination of keywords that are synonymous or related terms, along with acronyms and variant spellings. Your aim is to capture as much of the relevant literature as possible and search strings will help you do that.

There are a number of tools and search operators that you can use to improve the efficacy of your search strings.

Acronyms - If your keyword is also known by an acronym then both the full spelling and acronym should be searched, e.g., (“Armoured Fighting Vehicle” OR AFV).
Wildcard - If your keyword can be spelt differently, e.g., UK/US variants, then use a wildcard to capture both variations, e.g., defen?e will return papers with both defense and defence spellings.
Truncation - If your keyword could have several variant endings, then truncate it, e.g., technolog* will return papers with technology, technological, technologies, etc.
Phrase-searching – if your keyword has two or more words, then you should enclose the keywords within double quotation marks. If you do not, the database/search engine will put an invisible ‘AND’ operator between each word, e.g., systems engineering will be read by the database/search engine as systems AND engineering. This means that both systems and engineering must appear in the search results, but not necessarily together in the context of systems engineering. To ensure systems engineering is returned in your results as a phrase, search for “systems engineering”.

Note: Not all databases search using the same syntax, check the search tips of the database to check they accept wildcards, truncation, phrase-searching, etc. and adjust your search string accordingly.

Combining your keywords and search strings: search operators

OR - is used to combine synonyms, related terms, acronyms, etc. within search strings, e.g., (“Armo?red Fighting Vehicle*” OR AFV OR tank* OR “Infantry Fighting Vehicle*”) will return results where any one of these keywords appears. Using the OR operator expands your search results.
AND – is used to combine search strings of different concepts/themes, e.g., (“Armo?red Fighting Vehicle*” OR AFV OR tank* OR “Infantry Fighting Vehicle*” OR IFV OR “Armo?red Personnel Carrier*” OR APC) AND (protect* OR securit* OR IED OR "improvised explosive device*") will return results where any one keyword from the first search string and any one keyword from the second search strings appears in the document. Using the AND operator will narrow down your search results.
NOT/AND NOT – is used to eliminate keywords that you do not wish to appear in your search results, e.g., tank* NOT water will exclude results which contain the keyword water. Use this operator with caution, for example it is unlikely to exclude all results that mention water.

Watch this Boolean operators video to learn more about using them to connect your keywords and other commands such as quotation marks, question marks and asterisks which will all help you to improve your search results.

Covid W/3 (PPE OR “personal protective equipment”) will return results where Covid appears within three words of PPE or “personal protective equipment”, regardless of the order of the words.
Covid PRE/3 (PPE OR “personal protective equipment”) will return results where Covid appears first within three words of PPE or “personal protective equipment”.

Further guidance from Kings College London on advanced search techniques.

Search strategy

A search strategy is simply your search strings combined to address each of your review questions, to answer your overarching research topic. Search strings are usually combined with a Boolean operator or a proximity operator, as described above.

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Next: Limiters and filters >>
Last Updated: Feb 21, 2024 2:01 PM
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Combining keywords with Boolean operators

Conducting a good search requires a bit more than just putting single search terms in a search bar. In order to retrieve specific and targeted information about your topic, you need to logically combine search terms with each other. To do that, you use Boolean operators:

AND: if you are looking for references in which both search terms appear;
OR: if you are looking for references containing at least one of the search terms;
NOT: if you are looking for references in which a particular search term does not occur.

Note: Be careful when using NOT; it may exclude relevant articles by inadvertently (false negatives). A suggestion here is: run the search with and without the NOT, and see the difference by comparing the results in your Search History: how many results are omitted? Are the results that are omitted relevant to your search or not? Based on this, you can decide whether or not the NOT is a useful addition to your search string.

How to build a search string:

collect search terms and keywords by subtopic;
combine them with OR;
place the keywords between parentheses;
put an AND between the subtopics

Generic example: (... OR ... OR ... OR ... OR ...) AND (... OR ... OR ... OR ...) AND (... OR ... OR ... OR ... OR ...)

With this, you have created a basic search string that you can use for multiple databases. For some databases, you can fine-tune the search string by adding thesaurus terms and/or search fields (see below).

More tips and suggestions

Several techniques exist for fine-tuning your search string. Note that databases often have their own 'rules'. It is advisable to check per database which 'rules' apply to the syntax of your query. These can be found in the HELP or FAQ section of the database in question.

Exact word combination If you only want to find search results that contain the search terms in exactly that order, place your search terms inside double quotation marks ("....."), e.g. "Attention Deficit Hyperactivity Disorder."

Pro tip: an exact word combination is actually a strict version of the Boolean AND operator, where the search terms must also occur in that particular order. Therefore, the order of the search terms is not arbitrary, but set by you.

Truncation is a technique that can be used to expand your search; the end of a search term is replaced by a truncation mark, also known as a wildcard. Doing so allows you to efficiently find word variants and thus expand your search. For example:

child* = child, children, childhood, childhood, child-friendly, childs, child-like
industr* = industry, industries, industrial
genetic* = genetic, genetics

Truncation symbols may vary by database, but frequently used symbols include *, !, ? or #.

A wildcard is a symbol that replaces a letter of a word. This is especially useful when a word can be spelled several ways (but mean the same thing), such as in a British variant as an American variant. For example

wom!n = woman, women
colo?r = color, color
latin?= latina, latinx, latine, latino, latines

Search fields When you enter your basic search string into the search bar, your search terms will generally be checked to see if they appear anywhere in the text of the article. This can potentially create a lot of noise. Limiting your search to a to specific search fields will make it more focused. Advanced Search allows you to search only certain fields, e.g. title and/or abstract, keywords, or subject.

For example, "language development disorder"[abstract] AND "primary school"[abstract] AND "teaching materials"[abstract].

Note that each database has its own configuration and search fields, so always tailor your search to the database!

Minilecture Smart search

Useful links and resources

Useful links

See this link for a great visualization of a search string from a scoping paper .

If you have questions, please contact the Information Specialist Research of your research center , or go to support & contact for more information and advice.

[anchornavigation]

University of Michigan Library
Research Guides

Systematic Reviews

Search Strategy
Work with a Search Expert
Covidence Review Software
Types of Reviews
Evidence in a Systematic Review
Information Sources

Developing an Answerable Question

Creating a search strategy, identifying synonyms & related terms, keywords vs. index terms, combining search terms using boolean operators, a sr search strategy, search limits.

Managing Records
Selection Process
Data Collection Process
Study Risk of Bias Assessment
Reporting Results
For Search Professionals

Validated Search Filters

Depending on your topic, you may be able to save time in constructing your search by using specific search filters (also called "hedges") developed & validated by researchers in the Health Information Research Unit (HiRU) of McMaster University, under contract from the National Library of Medicine. These filters can be found on

PubMed’s Clinical Queries & Health Services Research Queries pages
Ovid Medline’s Clinical Queries filters or here
Embase & PsycINFO
EBSCOhost’s main search page for CINAHL (Clinical Queries category)
HiRU’s Nephrology Filters page
American U of Beirut, esp. for " humans" filters .
Countway Library of Medicine methodology filters
InterTASC Information Specialists' Sub-Group Search Filter Resource
SIGN (Scottish Intercollegiate Guidelines Network) filters page

Why Create a Sensitive Search?

In many literature reviews, you try to balance the sensitivity of the search (how many potentially relevant articles you find) & specificit y (how many definitely relevant articles you find ), realizing that you will miss some. In a systematic review, you want a very sensitive search: you are trying to find any potentially relevant article. A systematic review search will:

contain many synonyms & variants of search terms
use care in adding search filters
search multiple resources, databases & grey literature, such as reports & clinical trials

PICO is a good framework to help clarify your systematic review question.

P - Patient, Population or Problem: What are the important characteristics of the patients &/or problem?

I - Intervention: What you plan to do for the patient or problem?

C - Comparison: What, if anything, is the alternative to the intervention?

O - Outcome: What is the outcome that you would like to measure?

Beyond PICO: the SPIDER tool for qualitative evidence synthesis.

5-SPICE: the application of an original framework for community health worker program design, quality improvement and research agenda setting.

A well constructed search strategy is the core of your systematic review and will be reported on in the methods section of your paper. The search strategy retrieves the majority of the studies you will assess for eligibility & inclusion. The quality of the search strategy also affects what items may have been missed. Informationists can be partners in this process.

For a systematic review, it is important to broaden your search to maximize the retrieval of relevant results.

Use keywords: How other people might describe a topic?

Identify the appropriate index terms (subject headings) for your topic.

Index terms differ by database (MeSH, or Medical Subject Headings , Emtree terms , Subject headings) are assigned by experts based on the article's content.
Check the indexing of sentinel articles (3-6 articles that are fundamental to your topic). Sentinel articles can also be used to test your search results.

Include spelling variations (e.g., behavior, behaviour ).

Both types of search terms are useful & both should be used in your search.

Keywords help to broaden your results. They will be searched for at least in journal titles, author names, article titles, & article abstracts. They can also be tagged to search all text.

Index/subject terms help to focus your search appropriately, looking for items that have had a specific term applied by an indexer.

Boolean operators let you combine search terms in specific ways to broaden or narrow your results.

An example of a search string for one concept in a systematic review.

In this example from a PubMed search, [mh] = MeSH & [tiab] = Title/Abstract, a more focused version of a keyword search.

A typical database search limit allows you to narrow results so that you retrieve articles that are most relevant to your research question. Limit types vary by database & include:

Article/publication type
Publication dates

In a systematic review search, you should use care when applying limits, as you may lose articles inadvertently. For more information, see, particularly regarding language & format limits. Cochrane 2008 6.4.9

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Systematic Literature Review – Identifying your search terms and constructing your search strings

Our previous posts on the systematic review have looked at getting started and selecting your sources . In this post we will look at the next fundamental stage:

Identifying your search terms and constructing your search strings

Identifying your search terms

Having decided which sources you need to search, the next step in the systematic literature review process is to identify your search terms or keywords:

These may be individual words such as customer, or phrases like “ customer research management”. Note: if phrases are not inserted inside double quotation marks, each word will be searched for individually rather than as a phrase, e.g., customer AND service AND management instead of “customer service management”.
Your search terms should consist of not just the words which are included in your research question, but also synonyms (e.g. customer OR consumer), spelling variants , and any relevant concepts .
Spelling variants such as o rganization and organisation can be dealt with by using the wildcard symbol (‘?’) in place of a single letter. For example, a search for ‘ organi?ation’ will look for both spellings of the word. Note: not all sources accept the wildcard symbol. Check the search tips of your resource for guidance.
Use the truncation symbol (‘*’) at the end of a whole or partial word to search for variant word endings. For example, strateg * will find strategy, strategies, strategic etc. Note: not all sources accept the truncation symbol. Check the search tips of your resource for guidance.

When choosing your keywords, remember that the aim is to identify all relevant literature without making the search so broad that you retrieve lots of irrelevant material. For example, the synonyms for customer in the example below have been combined into a search string using the word OR:

(consumer OR customer OR client OR user)

Note that words such as individual or subject have not been included as these words are homographs and would produce a lot of irrelevant material. Homographs are words that are spelled the same but have more than one meaning. You should also only use ‘sensible synonyms’. For example, in gender studies you would not search using terms such as ‘gentleman’ or ‘lady’. These terms are unlikely to be used by the scholars in your field.

Constructing your search strings

Once you have chosen your keywords and phrases, they can be combined into search strings. Some examples of search strings are given below:

String 1 (“supply chain*” OR “supply network*” OR “demand chain*” OR “demand network*” OR “value chain*” OR “value network*”)

String 2 (“lead time compression” OR “lead time reduction” OR “cycle time compression” OR “cycle time reduction” OR “dwell time compression” OR “dwell time reduction”)

String 3 (agil* OR “quick response” OR speed*)

Note that each search string only contains synonyms or related terms.

Now that you have created your search strings, you are ready to construct your search strategies.

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Systematic Review

Systematic reviews

Being systematic

Search terms, choosing databases, finding additional resources.

Search techniques
Systematically search databases
Appraisal & synthesis
Reporting findings
Systematic review tools

Searching literature systematically is useful for all types of literature reviews!

However, if you are writing a systematic literature review the search needs to be particularly well planned and structured to ensure it is:

comprehensive
transparent

These help ensure bias is eliminated and the review is methodologically sound.

To achieve the above goals, you will need to:

create a search strategy and ensure it is reviewed by your research group
document each stage of your literature searching
report each stage of quality appraisal

Identify the key concepts in your research question

The first step in developing your search strategy is identifying the key concepts your research question covers.

A preliminary search is often done to understand the topic and to refine your research question.

Identify search terms

Use an iterative process to identify useful search terms for conducting your search.

Brainstorm keywords and phrases that can describe each concept you have identified in your research question.
Create a table to record these keywords
Select your keywords carefully
Check against inclusion/exclusion criteria
Repeated testing is required to create a robust search strategy for a systematic review
Run your search on your primary database and evaluate the first page of records to see how suitable your search is
Identify reasons for irrelevant results and adjust your keywords accordingly
Consider whether it would be useful to use broader or narrower terms for your concepts
Identify keywords in relevant results that you could add to your search to retrieve more relevant resources

Using a concept map or a mind map may help you clarify concepts and the relationships between or within concepts. Watch these YouTube videos for some ideas:

How to make a concept map (by Lucidchart)
Make sense of this mess world - mind maps (by Sheng Huang)

Example keywords table:

Research question: What is the relationship between adverse childhood experiences and depression in mothers during the perinatal period?

Revise your strategy/search terms until :

the results match your research question
you are confident you will find all the relevant literature on your topic

See Creating search strings for information on how to enter your search terms into databases.

Example search string (using Scopus's Advanced search option) for the terms in the above table:

(TITLE-ABS-KEY("advserse childhood experienc*" OR ACE OR "childhood trauma") AND TITLE-ABS-KEY("perinatal depress*" OR "postpartum depress*" OR "postnatal depress*" OR "maternal mental health" OR "maternal psychological distress") AND TITLE-ABS-KEY(mother* OR women*))

See Subject headings for information on including these database specific terms to your search terms.

Systematic reviewers usually use several databases to search for literature. This ensures that the searching is comprehensive and biases are minimised.

Use both subject-specific and multidisciplinary databases to find resources relevant to your research question:

Subject-specific databases: in-depth coverage of literature specific to a research field.
Multi-disciplinary databases: literature from many research fields - help you find resources from disciplines you may not have considered.

Check for databases in your subject area via the Databases tab > Find by subject on the library homepage .

Find the key databases that are often used for systematic reviews in this guide.

Test searches to determine database usefulness. You can consult your Liaison Librarians to finalise the list of databases for your review.

Recommendations:

For all systematic reviews we recommend using Scopus , a high-quality, multidisciplinary database:

Scopus is an abstract and citation database with links to full text on publisher websites or in other databases.
Scopus indexes a curated collection of high quality journals along with books and conference proceedings.
Research outputs are across a range of fields - science, technology, medicine, social science, arts and humanities.

For systematic reviews within the health/biomedical field, we recommend including Medline as one of the databases for your review:

MEDLINE (via Ebsco, via Ovid, via PubMed)

Medline is the National Library of Medicine’s (NLM) article citation database.
Medline is hosted individually on a variety of platforms (EBSCO, OVID) and comprises the majority of PubMed.
Articles in Medline are indexed using MeSH headings. See Subject headings for more information on MeSH.

Note: PubMed contains all of Medline and additional citations, e.g. books, manuscripts, citations that predate Medline.

To ensure your search is comprehensive you may need to search beyond academic databases when conducting a systematic review, particularly to find grey literature (literature not published commercially and outside traditional academic sources such as journals).

Google Scholar

Google Scholar contains academic resources across disciplines and sources types. These come from academic publishers, professional societies, online repositories, universities and web sites.

Use Google Scholar

as an additional tool to locate relevant publications not included in high-level academic databases
for finding grey literature such as postgraduate theses and conference proceedings

You can limit your search to the type of websites by using site:ac . nz; site:edu

Note that Google Scholar searches are not as replicable or transparent as academic database searches, and may find large numbers of results.

Other sources of grey literature

Grey literature checklist (health related grey literature)
OpenGrey
Public health Ontario guide to appraising grey literature
Institutional Repository for Information Sharing (IRIS)
Google search: use it for finding government reports, policies, theses, etc. You can limit your search to a particular type of websites by including site : govt.nz, site: . gov, site: . ac . nz, site: . edu, in your search

Watch our Finding grey literature video (3.49 mins) online.

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Next: Search techniques >>
Last Updated: Mar 13, 2024 9:39 AM
URL: https://aut.ac.nz.libguides.com/systematic_reviews

Conducting a Literature Review

Getting Started
Developing a Question
Searching the Literature
Identifying Peer-Reviewed Resources
Managing Results
Analyzing the Literature
Writing the Review

Need Help? Ask Your librarian!

Search Strategies

Boolean Operators

Once you have identified the key concepts of your research question (see "Developing a Question"), you can use those concepts to develop keywords for your search strategy. The following tips and techniques will help you design a precise and relevant search strategy.

Keywords are any words you might use to search the record of an article, book, or other material in library databases. The database searches through the metadata (such as title, authors, publication, abstract, etc.) to find resources that contain the word you searched, and may also search through the full text of the material.

Keywords are most successful when you're searching for the words that the authors use to describe the research topic, as most databases will search for those specific words within the record of the article. To increase your chance of returning relevant results, consider all of the words that might be used to describe the research you're trying to find, and try some of these out in sample searches to determine which words return the best results.

Search Tips - Keywords

Search for singular and plural terms together: (physician OR physicians)
Search for both the American and British spelling of words: (behavior OR behaviour)
Search for synonyms of terms together: (teenager OR adolescent)
Search for phrases inside of quotation marks: ("young adult")

Use Boolean operators to combine keywords for more precise search results.

AND - If the term must be included in your search:

influenza AND vaccine

OR - If terms are interchangeable, i.e. synonyms. Place OR'd terms within parentheses:

(influenza OR flu) AND vaccine

NOT - If a term should not be included in your search. This Boolean operator is rarely necessary for literature reviews.

(influenza OR flu) AND vaccine NOT H1N1

Note how we've used parentheses in the examples above. Search strings like these are similar to mathematical equations, where you perform the actions within the parentheses before proceeding from left to right to run the search. For example, using the search [(influenza OR flu) AND vaccine] will find results that have a term relating to influenza/flu, as well as the term vaccine.

If we moved the parentheses, it would be a very different search. [influenza OR (flu AND vaccine)] will provide results that use the term influenza, as well as results that use both the terms flu and vaccine. This means you would get results having to do with influenza but perhaps nothing to do with vaccination.

Here are a few examples of how this search would be different depending on the arrangement of booleans and keywords. The area highlighted in pink represents the search results that would be returned with this search.

Truncation allows you to quickly include all variations of a word in your search. Use the root of the keyword and add an asterisk (*). For example:

nurs* = nurse, nurses, nursing, nursery

IMPORTANT: Notice that "nursery" is also retrieved in the above search. Truncation will save you from having to include a large number of synonyms, but it will also add a certain number of irrelevant results. You can limit this effect by using the NOT Boolean operator, i.e. NOT nursery.

Wild cards allow you to replace a letter in a keyword to retrieve all variations of the spelling. For example:

p?ediatric = pediatric, paediatric

Free-Text vs. Thesaurus Searching

While you can search any word as a keyword, databases also contain an official list of the terms they use to describe the subject of each article, called Subject Headings. You can look up Subject Headings in the thesaurus of the database, using the thesaurus's search box to pull up the recommended Subject Heading for a given keyword. When searching specifically for Subject Headings, the database will only search the Subject Headings field within the record of each article (ie, not the title, abstract, etc.). This is a much more targeted method of searching, and is an excellent addition to your search strategy.

A strong search strategy will use both free-text (keyword) searching and thesaurus searching, to ensure that all relevant articles have been retrieved by the search. The lists below outline the strengths and weaknesses of both types of search strategies.

Free-Text Searching

Natural language words describing your topic
More flexible search strategy - can use any term in any combination
Database looks for keywords anywhere in the record - not necessarily connected together
May yield too many or too few results
May yield many irrelevant results

Thesaurus Searching

Pre-defined "controlled vocabulary" words used to describe the content of each item in a database
Less flexible search strategy - need to know the exact controlled vocabulary term
Database looks for subjects only in the subject heading or descriptor field, where the most relevant words appear
If too many results, you can use subheadings to focus on one aspect of a broader topic
Results are usually very relevant to the topic

MIT Libraries. Database Search Tips: Keywords vs. Subjects. https://libguides.mit.edu/c.php?g=175963&p=1160804

Each database has their own thesaurus. You will need to adapt your search strategy for each database to take advantage of their unique thesaurus.

PubMed uses MeSH terms (Medical Subject Headings). You can learn more about finding and using MeSH terms here:

The Basics of Medical Subject Headings (MeSH) in MEDLINE/PubMed: A Tutorial

CINAHL uses CINAHL Headings. You can learn more about finding and use these terms here:

Using CINAHL/MeSH Headings

In other databases, look for a link with the terms "headings", "subject headings", or "thesaurus" to find the appropriate thesaurus terms for your search.

Citation Searching

Citation searching is a search strategy that allows you to search either forward or backwards time through the literature based on an identified relevant article:

You can search forward in time by using databases that allow you to search for other articles that have cited the identified relevant article. (Web of Science and Google Scholar can do this automatically.)

Web of Science (Clarivate Analytics)
Google Scholar

You can search backward in time by reviewing the reference list of the identified relevant article for additional article citations.

For more information about how to perform citation searches, check out this guide from the University of Toledo Libraries:

How To: Cited Reference Searches in Web of Science Guide from the University of Toledo

Retrieving Materials

Select a database.

When searching for articles, it is best to use an appropriate subject database rather than the SearchIT catalog. Be sure to select your database from the Spokane Academic Library homepage to ensure that you will have access to full-text articles.

screenshot of Spokane Academic Library's frequently used databases

"Find It @ WSU" Button in PubMed

When you have found an article that you would like to read in its entirety, look for the "Find It @ WSU" Button. This button will take you to the article entry in the SearchIT catalog.

Here's what that looks like in PubMed.

screenshot showing the Find It @ WSU button on a PubMed article

"Find It @ WSU" Button in CINAHL

screenshot showing the Find It @ WSU button on a CINAHL article

"Find It @ WSU" Button in PsycINFO

screenshot showing the Find It @ WSU button on PsychINFO search results page

Accessing the Full-Text Article

After selecting the "Find It @ WSU" Button, you will be taken to the article entry in SearchIT. Select the link under the Access Options box to be directed to the full-text article.

screenshot of Search It item highlighting sign in and access links

If an article is not available in the WSU Libraries collection, you can request the article through interlibrary loan by selecting the link under "Access Options".

See the Using Interlibrary Loan section for more information.

screenshot of Search It item's access options

<< Previous: Developing a Question
Next: Identifying Peer-Reviewed Resources >>
Last Updated: Mar 6, 2024 11:04 AM
URL: https://libguides.libraries.wsu.edu/litreview

Systematic Reviews

Introduction
Review Process: Step by Step
1. Planning a Review
2. Defining Your Question & Criteria
3. Standards & Protocols

Designing Your Search Strategy

Search strategy checklists, pre-search tips, search strategies: filters & hedges, search terms, search strategies: and/or, phrase searching & truncation.

5. Locating Published Research
6. Locating Grey Literature
7. Managing & Documenting Results
8. Selecting & Appraising Studies
9. Extracting Data
10. Writing a Systematic Review
Tools & Software
Guides & Tutorials
Accessing Resources
Research Assistance

A well designed search strategy is essential to the success of your systematic review. Your strategy should be specific, unbiased, reproducible and will typically include subject headings along with a range of keywords/phrases for each of your concepts.

Your searches should be designed to capture as many studies as possible that meet your criteria.

Chapter 4 of the Cochrane Handbook for Systematic Reviews of Interventions provides detailed guidance for searching and study selection; see Supplement 3.8 Adapting search strategies across databases / sources for translating your search across databases.

Systematic Reviews: Constructing a Search Strategy and Searching for Evidence from the Joanna Briggs Institute provides step-by-step guidance using PubMed as an example database.

General Steps:

Locate previous/ relevant searches
Identify your databases
Develop your search terms and design search
Evaluate and modify your search
Document your search ( PRISMA-S Checklist)
Translate your search for other databases
Step by Step Systematic Review Search Checklist from MD Anderson Center Library
PRESS Peer Review Checklist for Search Strategies

Conduct a preliminary set of scoping searches in various databases to test out your search terms (keywords and subject headings) and locate additional terms for your concepts.

Try building a "gold set" of relevant references to help you identify search terms. Sources for this gold set may include:

Recommended key papers
Papers by known authors in the field
Results of preliminary searches from key databases such
Reviewing references and "cited by" articles lists for key papers
Articles that have been published in authoritative journals

Hedges/ Filters

PubMed Special Queries

Hedges are search strings created by experts to help you retrieve specific types of studies or topics; a hedge will filter your results by adding specific search terms, or specific combinations of search terms, to your search.

Hedges can be good starting points but you may need to modify the search string to fit your research. Resources for hedges:

University of Texas, School of Public Health (study type)
McMaster University Health Information Research Unit
The InterTASC Information Specialists' Sub-Group Search Filter Resource
Pubmed Search Strategies blog
PubMed Special Queries Topic-Specific PubMed Queries; includes keyword and search strategy examples.

Example: Health Disparities & Minority Health Search Strategies

Subject Headings
Keywords Vs. Subject Headings
Locating Subject Headings
Medical Subject Headings (MeSH)
Keyword & Subject Headings Logic Grid

You can use your PICOTS concepts as preliminary search terms. The important terms in this question:

In adults , is screening for depression and feedback of results to providers more effective than no screening and feedback in improving outcomes of major depression in primary care settings?

...might include:

Major depression

Primary Care

(From Lackey, M. (2013). Systematic reviews: Searching the literature [PowerPoint slides]. Retrieved from http://guides.lib.unc.edu/ld.php?content_id=258919 )

Your search will include both keywords and subject headings. Controlled vocabulary systems, such as the Medical Subject Headings (MeSH) or Library of Congress Subject Headings (LCSH) , use pre-set terms that are used to tag resources on similar subjects. See boxes below for more information on finding and using subject terms.

Not all databases will have subject heading searching and for those that do, the subject heading categories may differ between databases. This is because databases classify articles using different criteria.

Using the keywords from our example, here are some MeSH terms for:

Adults : Adult (A person having attained full growth or maturity. Adults are of 19 through 44 years of age. For a person between 19 and 24 years of age, YOUNG ADULT is available.)

Screening : Mass Screening (Organized periodic procedures performed on large groups of people for the purpose of detecting disease.)

Major depression : Depressive Disorder, Major (Marked depression appearing in the involution period and characterized by hallucinations, delusions, paranoia, and agitation.)

Here is a LCSH subject term for:

Depression : Depression, mental (Dejection ; Depression, Unipolar ; Depressive disorder ; Depressive psychoses ; Melancholia ; Mental depression ; Unipolar depression)

Most EBSCO databases have a tool to help you discover subject terms . See Academic Search Complete > Subject Terms and Academic Search Complete > Subject Terms: Thesaurus
Most ProQuest databases have a tool to help you discover subject terms: See PsycInfo > Thesaurus
When you find a useful article, look at the article's Subject Headings (or Subject or Subject Terms) , and record them as possible terms to use in a subject term search.

Here is an example of the subject terms listed for a systematic review found in PsycINFO, " Primary care screening for and treatment of depression in pregnant and postpartum women: Evidence report and systematic review for the US Preventive Services Task Force " (2016).

MeSH are standardized terms that describe the main concepts of PubMed/MedLine articles. Searching with MeSH can increase the precision of your search by providing a consistent way to retrieve articles that may use different terminology or spelling variations.

Note: new articles will not have MeSH terms; the indexing process may take up to a few weeks for newly ingested articles.

Use the MeSH database to locate and build a search using MeSH.

To search the MeSH database:

Search for 1 concept at a time.
If you do not see a relevant MeSH in the results, search again with a synonym or related term.
Click on the MeSH term to view to the complete record, subheadings, broader and narrower terms.

Build a search from the results list or from the MeSH term record to specify subheadings.

Select the box next to the MeSH term or subheadings that you wish to search and click Add to Search Builder.
You may need to switch AND to OR , depending on how you would like to combine terms.
Repeat the above steps to add additional MeSH terms. When your search is ready, click Search PubMed.

Logic Grid with Keywords and Index Terms or Subject Headings from Systematic Reviews: Constructing a Search Strategy and Searching for Evidence.

Bhuiyan, M. U., Stiboy, E., Hassan, M. Z., Chan, M., Islam, M. S., Haider, N., Jaffe, A., & Homaira, N. (2021). Epidemiology of COVID-19 infection in young children under five years: A systematic review and meta-analysis. Vaccine , 39 (4), 667–677. https://doi.org/10.1016/j.vaccine.2020.11.078

Boolean Logic: AND, OR, NOT
Phrase Searching " "
Truncation *
Proximity Searching

AND, OR, NOT

Join together search terms in a logical manner.

AND - narrows searches, used to join dissimilar terms OR - broadens searches, used to join similar terms

NOT - removes results containing specified keywords

#1 "major depression" AND "primary care"

#2 screen* OR feedback

#3 (screen* OR feedback)

AND “major depression”

AND “primary care”

"major depression" NOT suicide

" " To search for specific phrases, enclose them in quotation marks . The database will search for those words together in that order.

“ primary care ”

“ major depression ”

Truncate a word in order to search for different forms of the same word. Many databases use the asterisk * as the truncation symbol.

Add the truncation symbol to the word screen * to search for screen, screens, screening, etc.

You do have to be careful with truncation. If you add the truncation symbol to the word minor* , the database will search for minor, minors, minority, minorities, etc.

Not all databases support proximity searching. You can use these strategies in ProQuest databases such as Sociological Abstracts .

pre/# is used to search for terms in proximity to each other in a specific order; # is replaced with the number of words permitted between the search terms.

Sample Search: parent* pre/2 educational (within 2 words & in order )

This would retrieve articles with no more than two words between parent* and educational (in this order) e.g. " Parent practices and educational achievement" OR " Parents on Educational Attainment" OR " Parental Values, Educational Attainment" etc.

w/# is used to search for terms in proximity to each other in any order ; # is replaced with the number of words permitted between the search terms.

Sample Search: parent* w/3 educational (within 3 words & in any order )

This would retrieve articles with no more than three words between parent* and educational (in any order) e.g. "Educational practices of parents" OR "Parents value motivation and education" OR "Educational attainments of Latino parents"
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UOW Library
Key guides for students

Literature Review

How to search effectively.

Find examples of literature reviews
How to write a literature review
Grey literature

The Literature searching interactive tutorial includes self-paced, guided activities to assist you in developing effective search skills..

1. Identify search words

Analyse your research topic or question.

What are the main ideas?
What concepts or theories have you already covered?
Write down your main ideas, synonyms, related words and phrases.
If you're looking for specific types of research, use these suggested terms: qualitative, quantitative, methodology, review, survey, test, trend (and more).
Be aware of UK and US spelling variations. E.g. organisation OR organization, ageing OR aging.
Interactive Keyword Builder
Identifying effective keywords

2. Connect your search words

Find results with one or more search words.

Use OR between words that mean the same thing.

E.g. adolescent OR teenager

This search will find results with either (or both) of the search words.

Find results with two search words

Use AND between words which represent the main ideas in the question.

E.g. adolescent AND “physical activity”

This will find results with both of the search words.

Exclude search words

Use NOT to exclude words that you don’t want in your search results.

E.g. (adolescent OR teenager) NOT “young adult”

3. Use search tricks

Search for different word endings.

Truncation *

The asterisk symbol * will help you search for different word endings.

E.g. teen* will find results with the words: teen, teens, teenager, teenagers

Specific truncation symbols will vary. Check the 'Help' section of the database you are searching.

Search for common phrases

Phrase searching “...........”

Double quotation marks help you search for common phrases and make your results more relevant.

E.g. “physical activity” will find results with the words physical activity together as a phrase.

Search for spelling variations within related terms

Wildcards ?

Wildcard symbols allow you to search for spelling variations within the same or related terms.

E.g. wom?n will find results with women OR woman

Specific wild card symbols will vary. Check the 'Help' section of the database you are searching.

Search terms within specific ranges of each other

Proximity w/#

Proximity searching allows you to specify where your search terms will appear in relation to each other.

E.g. pain w/10 morphine will search for pain within ten words of morphine

Specific proximity symbols will vary. Check the 'Help' section of the database you are searching.

4. Improve your search results

All library databases are different and you can't always search and refine in the same way. Try to be consistent when transferring your search in the library databases you have chosen.

Narrow and refine your search results by:

year of publication or date range (for recent or historical research)
document or source type (e.g. article, review or book)
subject or keyword (for relevance). Try repeating your search using the 'subject' headings or 'keywords' field to focus your search
searching in particular fields, i.e. citation and abstract. Explore the available dropdown menus to change the fields to be searched.

When searching, remember to:

Adapt your search and keep trying.

Searching for information is a process and you won't always get it right the first time. Improve your results by changing your search and trying again until you're happy with what you have found.

Keep track of your searches

Keeping track of searches saves time as you can rerun them, store references, and set up regular alerts for new research relevant to your topic.

Most library databases allow you to register with a personal account. Look for a 'log in', 'sign in' or 'register' button to get started.

Literature review search tracker (Excel spreadsheet)

Manage your references

There are free and subscription reference management programs available on the web or to download on your computer.

EndNote - The University has a license for EndNote. It is available for all students and staff, although is recommended for postgraduates and academic staff.
Zotero - Free software recommended for undergraduate students.
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Systematic, Scoping, and Other Literature Reviews: Searching

Project Planning

Searching the Literature

Systematic and other major reviews involve a comprehensive search of the literature to ensure all studies that meet the predetermined criteria are identified. Typically key subject databases are searched first, after which the team might turn to less conventional search venues and explore what is known as grey literature - essentially any research that is shared outside of traditional publishing and distribution venues. Examples of grey literature include white papers, working papers, reports, government documents, and policy documents. And after screening the results found through these means, engaging in citation searching is recommended.

Review teams should develop search strategies that incorporate a mix of keywords and controlled vocabulary specific to the databases they're searching. Controlled vocabulary like the Medical Subject Headings (MeSH) used by PubMed and MEDLINE are standardized words and phrases that help enable the organization and retrieval of information in databases and other online venues.

Each research question is different, so the terms you'' use and the number and types of databases you'll search - as well as other online publication venues - will vary. Some standards and guidelines specify that certain databases (e.g., MEDLINE, EMBASE) should be searched regardless. Your subject librarian can help you select appropriate databases to search and develop search strings for each of those databases.

Commonly Searched Databases

Since systematic reviews began in the health sciences, searching PubMed, MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials is standard practice. These databases are listed below.

However, if you are conducting a review of the literature in another discipline, you will need to search the databases specific to that discipline. To begin, consult the library's complete list of databases or speak with your librarian.

PubMed PubMed is the National Library of Medicine's interface for MEDLINE, and also includes in-process and pre-1966 citations and other resources outside of MEDLINE. While basic PubMed is free to all Internet users, this link adds "Find it" buttons to individual citations that connect to the University of Nevada, Reno Libraries' journal subscriptions and document delivery services for full-text options.
MEDLINE via Ovid Updated daily, MEDLINE on the Ovid platform offers searchers seamless and up-to-the-minute access to over 23 million of the latest bibliographic citations and author abstracts from more than 5,600 biomedicine and life sciences journals in nearly 40 languages (60 languages for older journals). English abstracts are included in more than 80% of the records. Coverage dating back to 1946.
Embase An Elsevier database that covers the same subjects as PubMed/MEDLINE, with an additional focus on drugs and pharmacology, medical devices, clinical medicine, and basic science relevant to clinical medicine. 1947 - present (selectively back to 1902).
Cochrane Library The Cochrane Library contains the Cochrane Database of Systematic Reviews (CDSR), Cochrane Central Register of Controlled Trials (CENTRAL), and Cochrane Clinical Answers that offer different types of high-quality, independent evidence to inform healthcare decision-making.

Search Development Tools

Several online tools exist to help you identify controlled vocabulary, develop better search strings, and "translate" a search string developed for one database into one that works in another database. The tools listed below can assist you with one or more of these tasks. However, they are primarily aimed at and designed for teams and databases working in the health sciences.

Yale MeSH Analyzer
PubMed PubReMiner
MeSH on Demand

Grey Literature Search Tools

As noted above, searching the grey literature is also a key component of a good systematic review strategy. However, where to to search for such sources can vary a lot depending on the topic or field. Many researchers make use of the resources listed below. Please consult your librarian for more target assistance.

Google Advanced Search
OpenGrey "The System for Information on Grey Literature in Europe used to give open access to 700.000 bibliographical references of grey literature (paper) produced in Europe and allowed to export records and locate the documents."
govinfo "govinfo provides free public access to official publications from all three branches of the Federal Government."

Citation Searching

Citation searching is a method of searching the literature using citations rather than going to a database and conducting a search using keywords. It can help you better understand the scholarly landscape within your discipline and determine how your own work fits within that landscape. There are two types of citation searching: backward searching and forward searching.

Backward Citation Searching

When reading a work that’s very relevant to your research, you may want to examine the reference list closely to see which previously published works influenced the author(s). If you tracked down those cited works, you’d be engaging in what is known as backward citation searching.

Forward Citation Searching

Conversely, you may want to determine whether and by whom a given work has been cited after its publication – essentially, you’re wanting to know if other, newer works have included it in their reference lists. This is called forward citation searching.

The resources listed below can help you with citation searching.

Web of Science This collection contains over 21,000+ journals from 1900-present and includes: Science Citation Index , Social Sciences Citation Index , Arts and Humanities Citation Index and others. Search by subject, author, or cited reference. An excellent current awareness and bibliography-building tool.

citationchaser
ResearchRabbit
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Making Literature Reviews Work: A Multidisciplinary Guide to Systematic Approaches pp 145–200 Cite as

Search Strategies for [Systematic] Literature Reviews

Rob Dekkers 4 ,
Lindsey Carey 5 &
Peter Langhorne 6
First Online: 11 August 2022

1833 Accesses

3 Citations

After setting review questions as discussed in the previous chapter, the search for relevant publications is the next step of a literature review.

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JEL is the abbreviation of the ‘Journal of Economics Literature’, published by the American Economic Association, which launched this coding system.

Actually, Schlosser et al. ( 2006 , p. 571 ff.) call it ‘traditional pearl growing.’ The term ‘classical’ pearl growing has been adopted to ensure consistency throughout the book.

The wording ‘topical bibliography’ by Schlosser et al. ( 2006 , p. 574) has been replaced with ‘topical survey’ in order to connect better to the terminology in this book.

Webster and Watson ( 2002 , p. xvi) call it forward searching and backward searching rather than snowballing. See Table 5.3 for the nomenclature used in the book for search strategies.

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Dekkers, R., Carey, L., Langhorne, P. (2022). Search Strategies for [Systematic] Literature Reviews. In: Making Literature Reviews Work: A Multidisciplinary Guide to Systematic Approaches. Springer, Cham. https://doi.org/10.1007/978-3-030-90025-0_5

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Systematic Reviews

The Research Question
Inclusion and Exclusion Criteria
Original Studies
Translating
Deduplication
Project Management Tools
Useful Resources
What is not a systematic review?

Search Strings

Systematic review search strings can be incredibly complex. This is why it is fundamental to have an information specialist on the research team. For an example of a systematic review search strategy, please examine the document below to see additional information from M.D. Anderson Cancer Center Library.

Example Search String in 3 Databases
Preliminary Search
Exhaustive Search
Hand Search
Contact Experts

A preliminary search is about planning and developing your protocol . It helps the research team understand what the review would/should entail, and the preliminary search will also give an estimate for the time and funding commitment necessary for the investigation. Researchers should assume an exhaustive search will identify about 2-3 times more the number of citations than the preliminary search.

1. Searching for research trends

You need to see a sample of the research trends within the research area. You don’t know the general scope of the literature until you run a preliminary search. You must also sample these results for information for the background and objectives' section in the protocol.

A sampling of the preliminary results also helps you formulate the research question. The research question must be shaped by the pre-existing literature because enough pre-existing literature must exist in the first place to attempt to answer the research question.

2. Look to see if a systematic or scoping review already exists

Look to see if someone has already published a systematic/scoping review on your topic. This is again to analyze the research trends, but it is also important to not duplicate work that is already done.

3. Identifying preliminary MeSH/Subject Headings and keywords/keyphrases

You can identify the preliminary MeSH/subject headings, keywords, and key phrases you will need in your exhaustive search strategy. You will have more terms in your final search, but you must identify the basic subject headings and keywords you will need. This is the information that goes in your Search Methods section of your protocol. What goes in this Search Methods section of the protocol are the terms you found during your preliminary searching phase.

4. Getting test articles

Select 5-10 test articles from the preliminary search to use to test your future, exhaustive search strategy (i.e. the search to get your citations for your review). These 5-10 test articles should be articles that *should* make it to the end of review based on inclusion/exclusion criteria.
Researchers may have access to journal subscriptions. Being familiar with a journal and finding articles on the team's topic helps to see what research exists. It can help the information specialist find relevant subject headings and keywords for the search strategy. Additionally, the search strategy that is developed should be able to retrieve these articles that are known to directly address the team's research question.

5. Preparatory contacting of experts

One of t he goals of contacting experts is to identify unregistered studies with unpublished results. It is important to find experts on the research question because they will know what the current climate is on the research topic. Finally, the research team could benefit from this networking for later stages in the review.

The Exhaustive Search

This is the search designed by a librarian trained on how to design searches for systematic reviews. One goal of an exhaustive search is to identify all publications and as much grey literature as possible that meet study requirements. At least three databases should be utilized to conduct an exhaustive search. Another goal is to document and report the exhaustive search in such a way that it can be replicated for updates and reproduced by others after publication. See the Texas Medical Center Library's S.R. Database and Resources Libguide .

Study types and other considerations

There are many things to consider when searching for and identifying the literature relevant to the research question. Researchers should be familiar with the study types and their uses for systematic reviews.

Randomized Clinical Trials (RCTs): A study where there is an initial research question, and there are controls for population and the intervention to be studied. 'Randomized' refers to the population participants, where groups are divided into categories that either receive the studied intervention and those who receive the contemporary treatment or placebo.

Dissertations and unpublished research: The importance of searching for dissertations come into play when there is little research on a new or emerging topic. Additionally, within the published research there may already be problematic bias. Searching within these resources again helps reduce bias within the review.

Non-English studies: There may also be geographical bias in studies. It is important to search non-English studies to identify all the relevant literature for a topic.

Hand Search

Hand searching identifies grey literature like conference proceedings, abstracts for posters, and presented papers not indexed in online databases. Sources to hand search include: subject specific professional association websites; included studies' bibliographies; and topic review bibliographies. Hand searching can be done within research centers such as archives that house information resources out of circulation. It is important to document all sources searched by hand. Information regarding the number of hand searched resources used and where resources are located should be reported within the PRISMA Flow Diagram .

1. Clarification of the data

Some systematic reviews involve a meta-analysis. There may be questions regarding the data produced from the study. Contacting experts to clarify data findings helps develop better accuracy and transparency of the information that will be generated from the systematic review.

There are some systematic reviews, which require image analysis. Images that are used within published journals may not be easily synthesized or examined. The quality of the original image published in the journal article could make analysis difficult. Contacting the researchers for the raw data images will help the systematic review team better conduct image synthetization and analysis.

3. New developments

A systematic review can take 1-2 years. After the search strategy is developed the search has to be deduplicated. When a search is reran, some new articles may be retrieved. Being in contact with the experts helps the systematic review team know what other research is out there, so that information can be put into the review for the principle of transparency.

Caveats for searching

It is important to search three to five databases . The databases and how many you choose to search depends on the topic of the systematic review. Ultimately, be sure you consult with a librarian or information specialist before undertaking your searches for studies.

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Next: Original Studies >>
Last Updated: Oct 12, 2023 12:30 PM
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Conducting a winning literature search

Erika d. ecker.

1 Spectrum Research, Inc., Tacoma, Washington, USA

Andrea C. Skelly

So what is a “winning literature search”? Simply put, it is one that provides you with the information you need to find the types of articles that will help you with clinical practice or research. Literature searching is a combination of an art and a science. Understanding the basic anatomy and physiology of searching can get you started on finding the information you need.

I. Anatomy of a Literature Search—The Skeleton

A. constructing an appropriate question.

Asking the right question is the primary key to creating a winning search. Your questions must be answerable. If your question is too broad, your search will yield more information than you can possibly look through.

Similarly, if your study was prognostic rather than therapeutic, a PPO table would be used instead of the PICO table in order to help formulate your question. Thus, the categories would change to Patients, Prognostic factors, and Outcome.

⇛ Using treatment studies as an example, the PICO concept can really help you create an answerable question since, as you will see below, it will help you create a search strategy.

B. Using the appropriate database(s)

Now that you have honed your question, it is time to focus on efficient article retrieval. What type of information is needed and what type of articles do you need? What will you do with the information you gather? This will determine the type of information you need and types of articles that may provide that information. It also may influence the type of database you search for that information.

Bibliographic databases contain references to published literature, such as journals and newspaper articles, conference proceedings and papers, reports, government and legal publications, patents, and books.
Peer-reviewed literature is scholarly work that generally represents the latest original research in a field. These articles undergo expert screening before publication to ensure meaningfulness within the context of other research in the discipline and, at least in theory, sound methodology.
“Gray” literature refers to material that is not formally published by commercial publishers or peer-reviewed journals, including reports, fact sheets, white papers, conference proceedings, and other documents from various organizations and government agencies.

The table below provides brief descriptions of common databases and sources to search both peer-reviewed and gray literature.

For example, continuing with our question regarding complications after ADR versus fusion, which type of database listed in the table makes the most sense to search? Indexed peer-reviewed articles will give us the best available and most current data and MEDLINE, which includes millions of citations for biomedical articles and can be accessed using PubMed for free, seems like a great starting place. Generally speaking, PubMed will be the best place to begin your search and there are various ways, as you will see below, to refine and limit your search in order to find exactly what you need.

II. The Physiology of Literature Searching—How It Works

Now that you have an answerable question and an idea of what type of database you need to search (at least to start), let's talk about the nuts and bolts of searching. For the purposes of this paper, we will use PubMed as the search engine.

A. Getting specific—the basics of “how to”

1. Quickstart:

Type a word or phrase into the query box, including subject, author, and/or journal
Click on the search button or press the “enter” key

An external file that holds a picture, illustration, etc.
Object name is ebsj01009-1.jpg

To retrieve more information about the search results, use the display settings menu (upper left corner) to view the abstract or MEDLINE formats, change the number of items that appear per page, and sort by recently added, publication date, first author, last author, journal, or title.
PubMed also contains links to full-text articles (appears in upper right corner of page) at participation publishers' web sites as well as links to other third party sites such as libraries and sequencing centers.

⇛ Anything which appears in blue and is underlined is a link that reveals more information. Clicking on the title would bring up the abstract (Abstract format). Clicking on “Related articles” would provide a link to other similar articles that might be of interest.

2. Advanced searching in PubMed—MeSH terms and the MeSH database:

a. Medical subject headings (MeSH)

It is important to understand that PubMed uses a controlled vocabulary to index journal articles called MeSH and uses “automatic term mapping” to find MeSH terms when you search. MeSH terms are organized in a hierarchy called a tree, with more specific (narrower) terms arranged beneath broader terms. By default, PubMed includes in the search all narrower terms; this is called “exploding” the MeSH term. Inclusion of MeSH terms enhances and optimizes the search strategy. For example, if you looked up the term “Spine” in the MeSH database you would see see :

An external file that holds a picture, illustration, etc.
Object name is ebsj01009-2.jpg

Therefore, PubMed would retrieve every article containing any of the terms located under Spine in the hierarchy.

b. MeSH database features

MeSH vocabulary contains over 25,000 descriptors and is updated weekly and reviewed annually. You can only search citations that have been indexed for MEDLINE (92% of the PubMed database) using MeSH terms. Features include:

Allows you to identify and select appropriate MeSH terms for a search and to see their definitions
Builds a PubMed search strategy
Displays MeSH terms in the hierarchy (MeSH tree) allowing you to broaden/narrow a search
Limits MeSH terms to a major concept/topic heading for a search
Allows you to broaden your search by choosing not to explode a term
The list of subheadings includes terms paired at least once with a given heading in MEDLINE.
Focuses searches using other types of MeSH terms including publication types [pt], substance names [nm] or registry numbers [rn], and pharmaceutical actions [pa]
MeSH Brower for access to annotations: http://www.nlm.nih.gov/mesh/

To access MeSH from PubMed, click on MeSH Database on the PubMed homepage or click MeSH under “more resources” in “advanced search.”

Once in the MeSH database, if you entered cancer into the search bar and clicked Go (or hit Enter) you would see see :

An external file that holds a picture, illustration, etc.
Object name is ebsj01009-3.jpg

Clicking on “neoplasms” will bring up the page where you have the option of selecting any of the features listed above to help you refine your search.

Also, clicking “links” adjacent to the MeSH term desired, will give you a drop-down menu which offers several options:

PubMed: search PubMed with the term
PubMed—Major topic: search PubMed with the MeSH term, retrieving only citations where the term is a major focus
Clinical queries: put the MeSH term into the Clinical Queries box where the search may be further refined
NLM MeSH browser: show the MeSH browser descriptor data for this term including scope note, allowable qualifiers, and the MeSH tree

⇛ The Mesh database homepage includes three brief tutorials on how to search with the MeSH database, combine MeSH terms, and apply subheadings and other features of the MeSH database.

B. Too much information! Refining your search

Replace general search terms with more specific terms (the MeSH database would be a great resource for this)
AND between terms returns only records that contain all of the search terms
OR between terms returns all records that contain any of the search terms
NOT between search terms returns only records that contain the first term and not the second
Example: mimic* will find all terms that begin with the letters m-i-m-i-c-; eg, mimic, mimics, mimicking
Example: behavio?r will find behaviour or behavior
Use the “limit” option in PubMed to limit citations by age group, language, publication type, date, human studies, etc.
Use the “advanced search” option to look up a term as it is indexed in PubMed
Use the MeSH database features

Let's say we are interested in what the best surgical treatment is for osteoporotic spine fractures. Using some of the tips above, the chart below shows how a typical search might go: go:

By combining terms (using Boolean logic), truncating a term, and using the limits option we were able to narrow our search down from 16,023 articles to a more manageable and relevant 54 articles. The “details” tab in the PubMed search window shows the complete search expression (ie, query translation) employed by PubMed, similar to what is represented in the table above. above.

One of the best resources that PubMed provides for users new to the database is the online tutorials. They are brief but informative and because they are interactive you are guided step-by-step through each process. Perhaps consulting the online tutorials and the fact sheets on PubMed would be a next step for you. Give it a try! In fact, here is the link to the PubMed Tutorial homepage created by the National Library of Medicine: http://www.nlm.nih.gov/bsd/disted/pubmedtutorial/ . Also, check-out the PubMed help page which contains a plethora of information regarding all aspects of PubMed: http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=helppubmed&part=pubmedhelp

III. Closing Thoughts

Remember, literature searching is a combination of an art and a science. It requires practice, intuition, and some trial and error. While there is a basic structure, a set of guidelines and many tools for assisting one with basic searches, there are a variety of nuances and advanced techniques that may be required for more specialized searches. For systematic reviews as an example, extensive searches are required and may take numerous hours, involving many databases (including those for gray literature), and a combination of advanced search strategies in order to be methodologically sound. Use of personnel with specialized expertise in conducting such searches may provide the best results and be the most resource effective.

Literature Searching

In this guide.

Introduction
Steps for searching the literature in PubMed
Step 1 - Formulate a search question
Step 2- Identify primary concepts and gather synonyms
Step 3 - Locate subject headings (MeSH)
Step 4 - Combine concepts using Boolean operators
Step 5 - Refine search terms and search in PubMed
Step 6 - Apply limits

Steps for Searching the Literature

Searching is an iterative process and often requires re-evaluation and testing by adding or changing keywords and the ways they relate to each other. To guide your search development, you can follow the search steps below. For more information on each step, navigate to its matching tab on the right menu.

1. Formulate a clear, well-defined, answerable search question

Generally, the basic literature search process begins with formulating a clear, well-defined research question. Asking the right research question is essential to creating an effective search. Your research question(s) must be well-defined and answerable. If the question is too broad, your search will yield more information than you can possibly look through.

2. Identify primary concepts and gather synonyms

Your research question will also help identify the primary search concepts. This will allow you to think about how you want the concepts to relate to each other. Since different authors use different terminology to refer to the same concept, you will need to gather synonyms and all the ways authors might express them. However, it is important to balance the terms so that the synonyms do not go beyond the scope of how you've defined them.

3. Locate subject headings (MeSH)

Subject databases like PubMed use 'controlled vocabularies' made up of subject headings that are preassigned to indexed articles that share a similar topic. These subject headings are organized hierarchically within a family tree of broader and narrower concepts. In PubMed and MEDLINE, the subject headings are called Medical Subject Headings (MeSH). By including MeSH terms in your search, you will not have to think about word variations, word endings, plural or singular forms, or synonyms. Some topics or concepts may even have more than one appropriate MeSH term. There are also times when a topic or concept may not have a MeSH term.

4. Combine concepts using Boolean operators AND/OR

Once you have identified your search concepts, synonyms, and MeSH terms, you'll need to put them together using nesting and Boolean operators (e.g. AND, OR, NOT). Nesting uses parentheses to put search terms into groups. Boolean operators are used to combine similar and different concepts into one query.

5. Refine search terms and search in PubMed

There are various database search tactics you can use, such as field tags to limit the search to certain fields, quotation marks for phrase searching, and proximity operators to search a number of spaces between terms to refine your search terms. The constructed search string is ready to be pasted into PubMed.

6. Apply limits (optional)

If you're getting too many results, you can further refine your search results by using limits on the left box of the results page. Limits allow you to narrow your search by a number of facets such as year, journal name, article type, language, age, etc.

Depending on the nature of the literature review, the complexity and comprehensiveness of the search strategies and the choice of databases can be different. Please contact the Lane Librarians if you have any questions.

The type of information you gather is influenced by the type of information source or database you select to search. Bibliographic databases contain references to published literature, such as journal articles, conference abstracts, books, reports, government and legal publications, and patents. Literature reviews typically synthesis indexed, peer-reviewed articles (i.e. works that generally represent the latest original research and have undergone rigorous expert screening before publication), and gray literature (i.e. materials not formally published by commercial publishers or peer-reviewed journals). PubMed offers a breadth of health sciences literature and is a good starting point to locate journal articles.

What is PubMed?

PubMed is a free search engine accessing primarily the MEDLINE database of references and abstracts on life sciences and biomedical topics. Available to the public online since 1996, PubMed was developed and is maintained by the National Center for Biotechnology Information (NCBI) , at the U.S. National Library of Medicine (NLM) , located at the National Institutes of Health (NIH) .

MEDLINE is the National Library of Medicine’s (NLM) premier bibliographic database that contains more than 27 million references to journal articles from more than 5,200 worldwide journals in life sciences with a concentration on biomedicine. The Literature Selection Technica Review Committee (LSTRC) reviews and selects journals for MEDLINE based on the research quality and impact of the journals. A distinctive feature of MEDLINE is that the records are indexed with NLM Medical Subject Headings (MeSH).

PubMed also contains citations for PubMed Central (PMC) articles. PMC is a full-text archive that includes articles from journals reviewed and selected by NLM for archiving (current and historical), as well as individual articles collected for archiving in compliance with funder policies. PubMed allows users to search keywords in the bibliographic data, but not the full text of the PMC articles.

How to Access PubMed?

To access PubMed, go to the Lane Library homepage and click PubMed in "Top Resources" on the left. This PubMed link is coded with Find Fulltext @ Lane Library Stanford that links you to Lane's full-text articles online.

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Last Updated: Jan 9, 2024 10:30 AM
URL: https://laneguides.stanford.edu/LitSearch

COMMENTS

Search strings
Search strings are a combination of keywords that are synonymous or related terms, along with acronyms and variant spellings. Your aim is to capture as much of the relevant literature as possible and search strings will help you do that. There are a number of tools and search operators that you can use to improve the efficacy of your search ...
Building your search string
Search fields When you enter your basic search string into the search bar, your search terms will generally be checked to see if they appear anywhere in the text of the article. This can potentially create a lot of noise. Limiting your search to a to specific search fields will make it more focused.
A systematic approach to searching: an efficient and complete method to
INTRODUCTION. Librarians and information specialists are often involved in the process of preparing and completing systematic reviews (SRs), where one of their main tasks is to identify relevant references to include in the review [].Although several recommendations for the process of searching have been published [2-6], none describe the development of a systematic search strategy from ...
Research Guides: Systematic Reviews: Search Strategy
Creating a Search Strategy. A well constructed search strategy is the core of your systematic review and will be reported on in the methods section of your paper. The search strategy retrieves the majority of the studies you will assess for eligibility & inclusion. The quality of the search strategy also affects what items may have been missed.
Systematic Literature Review
Identifying your search terms and constructing your search strings; Identifying your search terms. Having decided which sources you need to search, the next step in the systematic literature review process is to identify your search terms or keywords: These may be individual words such as customer, or phrases like "customer research ...
How to carry out a literature search for a systematic review: a
A literature search is distinguished from, but integral to, a literature review. Literature reviews are conducted for the purpose of (a) locating information on a topic or identifying gaps in the literature for areas of future study, (b) synthesising conclusions in an area of ambiguity and (c) helping clinicians and researchers inform decision-making and practice guidelines.
Library Guides: Systematic Review: Developing a search strategy
Revise your strategy/search terms until:. the results match your research question; you are confident you will find all the relevant literature on your topic; See Creating search strings for information on how to enter your search terms into databases.. Example search string (using Scopus's Advanced search option) for the terms in the above table:
Step 3: Develop a Systematic Review Search Strategy
A systematic review aims to review as much of the literature as possible to minimize bias. As such, it is recommended that at least 3 databases are searched for a systematic review. ... The search string above is searching with both keywords and MeSH terms. The MeSH terms will be searched in the MeSH field. The keywords will be searched in all ...
LibGuides: Literature Reviews: Developing a Search Strategy
The search string above was developed for PubMed. When adapting the string for another database, you want to have the strings operate as similarly as possible. You would replace the MeSH terms with the controlled vocabulary of the other databases used. The search string above is searching with both keywords and MeSH terms. The MeSH terms will ...
Step 3: Develop a Systematic Search Strategy
A scoping review aims to review as much of the literature as possible to minimize bias. As such, it is recommended that at least 3 databases are searched for a scoping review. ... The search string above is searching with both keywords and MeSH terms. The MeSH terms will be searched in the MeSH field. The keywords will be searched in all fields ...
Search Strategy
The Search Strategy Builder is a tool designed to teach you how to create a search string using Boolean logic. While it is not a database and is not designed to input a search, you should be able to cut and paste the results into most databases' search boxes. Brainstorm keywords related to your topic, then enter your search statement here.
Research Guides: Literature Reviews: Develop Search Strategies
Search for your topic in Web of Science and Scopus (with no date limits), and sort the results by Times Cited or Cited by to see the most cited articles in the area. Use caution, however. Some articles are highly cited because the research is controversial. Read the literature review sections of other dissertations on the same or related topic.
Searching the Literature
The lists below outline the strengths and weaknesses of both types of search strategies. Free-Text Searching. Natural language words describing your topic. More flexible search strategy - can use any term in any combination. Database looks for keywords anywhere in the record - not necessarily connected together.
4. Search Terms & Strategies
Systematic Reviews: Constructing a Search Strategy and Searching for Evidence from the Joanna Briggs Institute provides step-by-step guidance using PubMed as an example database. General Steps: Locate previous/ relevant searches. Identify your databases. Develop your search terms and design search. Evaluate and modify your search.
Guides: Literature Review: How to search effectively
Specific proximity symbols will vary. Check the 'Help' section of the database you are searching. 4. Improve your search results. All library databases are different and you can't always search and refine in the same way. Try to be consistent when transferring your search in the library databases you have chosen.
Systematic Reviews: Step 3: Conduct Literature Searches
Systematic review quality is highly dependent on the literature search(es) used to identify studies. To follow best practices for reporting search strategies, as well as increase reproducibility and transparency, document various elements of the literature search for your review.
Systematic, Scoping, and Other Literature Reviews: Searching
As noted above, searching the grey literature is also a key component of a good systematic review strategy. However, where to to search for such sources can vary a lot depending on the topic or field. Many researchers make use of the resources listed below. Please consult your librarian for more target assistance.
Search Strategies for [Systematic] Literature Reviews
A search strategy is the method by which relevant sources are found, usually by searching selected databases and search engines using a mix of keywords, controlled vocabulary and search operators. Relevance is determined by a review question for which guidelines can be found in Sections 4.2 and 4.3.
Literature review papers: the search and selection process
Literature review papers (LRPs) form a major contribution to the output of scientific research. They introduce readers efficiently into a specific research area by providing an overview of the state of knowledge. Literature reviews should not only provide an overview but also add value, examples being the gaps in research and a research agenda ...
Searching
Systematic review search strings can be incredibly complex. This is why it is fundamental to have an information specialist on the research team. For an example of a systematic review search strategy, please examine the document below to see additional information from M.D. Anderson Cancer Center Library.
Conducting a winning literature search
Clicking on "neoplasms" will bring up the page where you have the option of selecting any of the features listed above to help you refine your search. Also, clicking "links" adjacent to the MeSH term desired, will give you a drop-down menu which offers several options: PubMed: search PubMed with the term.
Steps for searching the literature in PubMed
To guide your search development, you can follow the search steps below. For more information on each step, navigate to its matching tab on the right menu. 1. Formulate a clear, well-defined, answerable search question. Generally, the basic literature search process begins with formulating a clear, well-defined research question.
How to Perform a Literature Search
Phase 1. To begin, perform a title and/or abstract review of the papers. Read the title, and the abstract if necessary, of each paper to evaluate whether the article should be included in a future review. If you are unsure, keep the article in the included list for now.
Guidelines for the search strategy to update systematic literature
It used the same search string and protocol as in the original SLR. In total, the SLR-update identified 11 primary studies, and missed studies S22 to S25. The first replication of SLR-update ... An Update to the Systematic Literature Review of Empirical Evidence of the Impacts and Outcomes of Computer Games and Serious Games. Comput Educ, 94 (1

Writing your thesis and conducting a literature review

Search strings

Building your search string

Combining keywords with Boolean operators

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Minilecture Smart search

Useful links and resources

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Systematic Reviews

Developing an Answerable Question

Validated Search Filters

Why Create a Sensitive Search?

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Systematic Review

Being systematic

Identify the key concepts in your research question

Identify search terms

Example keywords table:

Recommendations:

Google Scholar

Other sources of grey literature

Conducting a Literature Review

Need Help? Ask Your librarian!

Search Strategies

Free-Text vs. Thesaurus Searching

Free-Text Searching

Thesaurus Searching

Citation Searching

Retrieving Materials

"Find It @ WSU" Button in PubMed

"Find It @ WSU" Button in CINAHL

"Find It @ WSU" Button in PsycINFO

Accessing the Full-Text Article

Systematic Reviews

Designing Your Search Strategy

Literature Review

1. Identify search words

2. Connect your search words

Find results with two search words

Exclude search words

3. Use search tricks

Search for common phrases

Search for spelling variations within related terms

Search terms within specific ranges of each other

4. Improve your search results

Narrow and refine your search results by:

When searching, remember to:

Keep track of your searches

Manage your references

Systematic, Scoping, and Other Literature Reviews: Searching

Searching the Literature

Commonly Searched Databases

Search Development Tools

Grey Literature Search Tools

Citation Searching

Backward Citation Searching

Forward Citation Searching

Search Strategies for [Systematic] Literature Reviews

Buying options

Author information

Rights and permissions

Copyright information

About this chapter

Download citation

Share this chapter

Systematic Reviews

Search Strings

The Exhaustive Search

Study types and other considerations