Searching

Grey literature

To ensure a truly comprehensive search and to prevent publication bias from playing a role in the results of your systematic review, other sources beyond journal literature databases should be considered. This is known as grey literature searching, which aims to find literature beyond what is published in traditional publication venues. Grey literature can include things like government documents, professional association guidelines, theses and dissertations, industry reports, whitepapers, and more.

The type and amount of grey literature searching needed will depend on your research question – there is no one correct way to carry it out. Grey literature searching requires you to think about the kinds of organizations and venues that might be creating documents that are of relevance to your research question.

Once you have identified the organizations that might be producing documents pertinent to your review, you will need to determine where those documents are kept. This may involve a keyword search of the organization’s webpage or navigating to a page on their site that holds their publications.

A Google search is another potential strategy you can use to find grey literature. See here for more information about running Google searches for grey literature (Simon Fraser University).

It is important to document the sources, search strategies, and results of your grey literature searching. This ensures reproducibility in your review methods.

Some sources to consider include (but are not limited to):

• Government Documents: see the Concordia Library's guide to finding Government Information
• Health Canada's Clinical Trials Database
• Canadian Clinical Practice Guidelines: CPG Infobase
• CADTH Grey Matters: searchable tool of grey literature sources (health organizations)
• New York Academy of Medicine Grey Literature Report: No longer updated, but still accessible
• Theses and dissertations: Try searching ProQuest Dissertations & Theses Global, but also, institutional repositories often store these kinds of documents (e.g., Spectrum: Concordia University's open access research repository)
• Canada Commons: Canadian public policy papers from think tanks, government and research organizations.

Your subject librarian may also be able to help you identify good sources for your grey literature search. This grey literature guide from the University of Toronto, and these guides from the University of British Columbia (Health Sciences or Non-Health Subjects) provide additional sources for grey literature searching.