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Systematic Review

Resources for conducting a systematic review research.

Searching the literature

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Image: The History of Private Search Engines by Christian Stewart

Begin your search journey with a librarian!

Librarians can recommend databases and other sources to search for a systematic review. Check Database Finder for a full list of available sources across all disciplines.

Librarians can also help with designing complex searches using the specialized syntax of individual databases. Consult your subject librarian, if you have questions.

Search more databases to limit bias! Why?

The more resources, the better

“The conduct of the search for and selection of evidence may have serious implications for patients’ and clinicians’ decisions. A systematic review might lead to the wrong conclusions and, ultimately, the wrong clinical recommendations.” 


Finding Existing Systematic Reviews

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Searching for existing systematic reviews on a topic related to your own research question can be a good place to start. These systematic reviews may provide a model for approaching your own review of the literature, including recommended search strategies and resources. 

The following are links to online libraries of systematic reviews and evidence documents for health and other areas of policy-making.

Check the Search Strategy Used to Create the Systematic Reviews Subset on PubMed

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Appraising Systematic Reviews

Just because a review has been published as a "systematic review", it does not imply that the review was rigorous, reproducible or exhaustive. There are a number of criteria by which you can assess the quality of a systematic review.

The following article summarizes 44 critical appraisal tools.

Crowe, M., & Sheppard, L. (2011). A review of critical appraisal tools show they lack rigor: Alternative tool structure is proposed. Journal of Clinical Epidemiology, 64(1), 79–89.

Below are some common tools used for this purpose.

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Database Syntax

Every database works differently. Consult with a librarian to 'translate' searches between databases. The link below provides some guidance for how to search using different platforms.

  • Database syntax guide - A guide to database syntax provided by the Effective Practice and Organization of Care Cochrane Review group (EPOC).

In addition to subject databases found in UMD Libraries' Database Finder list:

... consult the list of databases below for a more comprehensive search.

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How many and which databases to choose from?

The more resources, the better

There are systematic reviews in many subject areas such as education, social work, and even engineering where different databases are appropriate and very different conclusions would be reached. Some research is suggested below:

Suggested databases for different subject areas

Agriculture, food and nutrition


Human health and medicine


Organizational development, economics and policy

Psychology, human development and other social sciences

Reproductive health and women


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This tab provides databases around the globe to find systematic reviews and other scholarly literature from national and international sources.

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What is grey literature?

Gray literature is defined by the Cochrane Handbook for Systematic Reviews of Interventions as "...literature that is not formally published in sources such as books or journal articles." This can include information such as government reports, conference proceedings, graduate dissertations, unpublished clinical trials, and much more.  

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Document your searches using the CADTH Grey Matters checklist, p. 3. It is a MS Word document where you fill in the blanks to say which website you searched, when you searched it, etc. 

How to find grey literature?

Tips and tricks
Comprehensive guides with resources
Free databases of grey literature
Theses and dissertations

UMD restricted access

International databases

Conference Proceedings