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Grey Literature

What, Why, Where & How of Gray Literature

Grey Literature Databases

The databases below are designed specifically to search for hard-to-find grey literature. Note that many of these databases have unsophisticated search systems, so it can be difficult to build a focused search strategy for them. For assistance using these databases, reach out to your liaison librarian.

Searching Organization Websites

One of the best ways to find relevant grey literature is to go straight to the websites of organizations that do research and work in your area of interest, as these organizations often produce reports, white papers, and other forms grey literature. In addition to using your own professional knowledge, you can use the sources below to identify relevant organizations in your research area.

Academic Databases

While most academic databases do not include grey literature, some of our databases include selected grey literature, particularly conference proceedings and dissertations. The list below introduced some databases that include grey literature and the types of content they include. Developing a comprehensive search with lots of keywords in the following databases will help you include grey literature without having to search many additional sources.

Government Information

Government agencies produce a wealth of information via reports, white papers, policy papers, and more. The library's A-Z database list contains a wide variety of recommended government websites to find high-quality information. See below for a list of some key government resources to consider for your search.

Clinical Trial Registries

Trials registers

The two key registers you should start with are ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP).

The ICTRP enables searching across multiple national registers. ClinicalTrials.gov is an increasingly important international register for systematic reviews. It can be searched through the ICTRP, but its more advanced search features make an additional, direct search of this register worthwhile to find the largest possible number of relevant studies.

Not only do trials registers provide access to ongoing, unpublished studies, but they also provides access to a growing repository of information on completed studies, many of which have results posted on the site (irrespective of the publication status of the study). 

Preprints

Preprints are versions of research articles that are posted in a public repository BEFORE being accepted to a journal or undergoing peer review. They can be a great way to follow current research on a topic without waiting the long publishing process. Because preprints have not been peer reviewed, it is important to critically appraise them yourself. 

Important preprint servers in the health sciences are listed below. 

Dissertations and Theses

Dissertations and theses are normally not indexed in general bibliographic databases such as MEDLINE or Embase, but there are exceptions, such as CINAHL, where nursing, physiotherapy, and occupational health dissertations are indexed, and PsycINFO, where dissertations in psychiatry and psychology are indexed. To identify relevant studies published in dissertations or theses, it is advisable to search specific dissertation sources.