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Systematic Reviews

This guide provides tips and strategies for conducting a systematic literature review.

Search Tips

An important part of a systematic review is letting readers know exactly when and how you did your search.

Boolean Operators

Understanding how to use Boolean operators (AND, OR, and NOT) can help you get a much better set of results.

dog AND cat:    The search has to find both search terms

dog OR cat:      The search has to find at least one of the search terms

dog NOT cat:    A record has to contain "dog" but must not contain "cat" [Use very sparingly since relevant results may be excluded]

The asterisk is the most common truncation symbol. It tells the database to find any word beginning with the letters before the asterisk.

environment*     Looks for the terms environment, environments, environmental, etc.

Searching by phrase

Place phrases in quotation marks. (In Scopus, this is considered a loose phrase. Use {phrase} for an exact phrase in Scopus)

"pet therapy"     Searches these words as a phrase


Use parentheses to group search terms together. The following search string requires that the word "nutrition" appear in the record, but only one of the terms "dogs" or "cats" has to appear.

(dogs OR cats) AND nutrition

Subject Headings

Understand the subject headings (special indexing terms) used by each database. Search terminology that is effective in one database may not be effective in another.

Search Parameters

At the beginning of the process, you will want to do some initial searching to get a feel for what has been published. This may help you to determine some general criteria for publications. Examples of questions to ask are ...

  • In addition to peer-reviewed journal articles, will you include other types of sources (such as conference papers, books, theses, reports, etc.)?
    • Note: The same study may appear in different types of sources.
  • Will you only search for publications that fall within a certain timeframe?
  • Will you limit to publications in certain languages?

For all of these, you should be prepared to provide reasons for your decisions in the Methods section of your paper.

Searching Multiple Databases Simultaneously

The library subscribes to many databases through the EBSCO company. Examples include Academic Search Premier, Environment Complete, and ERIC. These database can be searched simultaneously, but note the following:

“Authors may choose to search multiple databases at once through a single search platform to increase efficiency. Along with the name of the platform, it is necessary to list the names of each of the individual databases included as part of the search. Including information about using this approach in the text of the manuscript helps readers immediately understand how the search was constructed and executed. This helps readers determine how effective the search strategy (Table 2) will be for each database [1].”

Source: Rethlefsen, M. L., Kirtley, S., Waffenschmidt, S., Ayala, A. P., Moher, D., Page, M. J., Koffel, J. B., & PRISMA-S Group (2021). PRISMA-S: an extension to the PRISMA Statement for Reporting Literature Searches in Systematic Reviews. Systematic Reviews, 10(1), 39.

Search Filters for Randomized Controlled Trials