It is mandatory to document the search process for each database, including all search terms & variations, the date when the searches were carried out, how many results you retrieved for each search, how many records were duplicates, & the final number of results that you used for your first pass.  PRISMA, which you can find on the Planning page of this research guide, provides standards for the type of information that you should include.​

Librarians can recommend databases to search for your evidence synthesis; the databases you choose will depend on your research question and the disciplines in which relevant research may be conducted. Below is some guidance for choosing scholarly databases in a number of research areas. Check the WMU Libraries' databases and resource guides for available sources across all disciplines.

Every database works differently. Your librarian can help with designing complex searches using the specialized syntax of individual databases and 'translate' searches between databases.

Grey (or gray) literature is literature produced by individuals or organizations outside of commercial and/or academic publishers. This can include information such as government reports, conference proceedings, graduate dissertations, unpublished clinical trials, and much more.  The sources you select will be informed by your research question and field of study. Your librarian can advise you on techniques to find and search gray literature sources, including (but not limited to): 

• Dissertation and thesis databases
• Clinical trials and studies (including those that did not produce the expected effect)
• Government agencies (local, state, federal, international)
• Nonprofit organizations and NGOs
• Conference proceedings
• Technical reports
• Professional and disciplinary newsletters
• Trade magazines
• Known experts

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

You will use both Keywords and Index/Subject Terms in your search. 

Use keywords:  How other people might describe a topic?

• 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.

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

• Index/subject terms help to focus your search appropriately, looking for items that have had a specific term applied by an indexer.
• Index terms differ by database (MeSH/Medical Subject Headings, Subject headings, Descriptors) 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). 

Below is an example of a search string for one concept in a systematic review, including both keywords and index terms, and multiple spelling variations.

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

Boolean logic is an important component of writing a search strategy: 

• "AND" narrows the search, e.g. children AND exercise
• "OR" broadens the search, e.g. (children OR adolescents) AND (exercise OR diet) 
• "NOT" excludes terms, e.g. exercise NOT diet 
• "*" at the root of a word finds all forms of that word, e.g. (child* OR adolescen*) AND (exercise* OR diet*)
• parentheses ensure all terms will be searched together as a set 
• quotations around a phrase searches that exact phrase, e.g. (child* OR adolescen* OR "young adult*") 

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
• Species
• Language
• Sex
• Subject
• Ages

In a systematic review search, you should use care when applying limits, as you may lose articles inadvertently.