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Systematic Reviews for Health: Grey Literature

A guide on how a Research Librarian can help you during a systematic review process

Grey Literature

Grey literature is the "wealth of knowledge and information produced by organizations, governments and industry, covering a wide range of subject areas and professional fields, not controlled by commercial publishing." (Pisa Declaration 2014)

When conducting a systematic review it is important to include literature that has not formally been published in sources as it helps to prevent publication bias. Searching grey literature is supported/mandated by the Cochrane Collaboration, the Campbell Collaboration, JBI and the Institute of Medicine (U.S.).

Grey Literature Searching Approach

  1. Scope for key systematic reviews on your topic and explore what grey literature options are mentioned in Methods section.

  2. Search relevant bibliographic databases that contain grey literature material, particularly dissertations & theses and conference papers.

  3. Explore grey databases.

  4. Consult trials registers to detect ongoing and unpublished studies.

  5. Find publications on web sites of key organisations, professional associations, government departments/services and key authors.

  6. Search Google Advanced/Google Scholar.

TIP!  Conduct broad searches and document which resources you search.

Grey Literature Guides

These guides may help you decide which grey literature to search:

Dissertations & Theses

There are dissertations/theses specific databases such as ProQuest Dissertations & Theses.

The Theses subject guide contains information on how to search for UTAS theses, Australian theses and International theses.

Google Scholar includes dissertations/theses.

Some bibliographic databases include dissertations/theses: CINAHLPsycINFO and SportDiscus.

Conference Abstracts & Proceedings

Google Scholar includes conference papers.

Various bibliographic databases also include conference papers: CINAHL, Scopus, SportDiscus and Web of Science.

Relevant key organisations may hold conferences and make their proceedings available. Examples:

Web Sites

Review publications on websites of relevant government departments, organisations and foundations as well as professional associations:


Appraising Grey Literature

The Flinders University developed a useful tool for evaluating grey literature:

Types of Grey Literature

Grey Databases and Directories

Trial Registers

Many clinical trials are grey or unpublished. When appropriate, it's important to include unpublished and ongoing studies to minimise bias (Cochrane Handbook, 4.3.3).

Google Advanced

Limit searches by site/domain or filetype, e.g.

  • filetype:pdf

Source Information

Information on this page is mainly drawn from:

Tyndall, J 2016, Systematic review searching: Grey literature, Australian Evidence Based Practice Librarians’ Institute, Flinders University, Adelaide, 9 December 2016.

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