Grey Literature

  • Learn about grey literature as a research source
  • Build your confidence in finding and evaluating grey literature resources
  • Discover the help and support that is available

Grey literature is defined as "information produced on all levels of government, academics, business and industry in electronic and print formats not controlled by commercial publishing" ie. where publishing is not the primary activity of the producing body." —ICGL Luxembourg definition, 1997. Expanded in New York, 2004.Grey literature can also mean literature that is hard to find or has inconsistent or missing bibliographic information. 

Grey literature can also mean literature that is tricky to find and identify as such or has inconsistent or missing bibliographic information. 

Why use it?

  • Monitor changes in a particular field
  • Balance for publication bias found in published literature.
  • Locate experts in a field
  • Rapidly produced and very current
  • Current state of affairs and historical collections
  • Unpublished research

Examples of grey literature include:

technical or research reports pamphlet speeches
committee reports conference presentations preprint materials
market reports blogs theses and dissertations
conference papers emails newsletters
white papers podcasts clinical trials
poster government documents maps

Extensive list provided by GreyNet International.

Who "produces" grey literature?

Narrow down the focus of your search

  • What kinds of information are you looking for?
    • theses and dissertations?
    • conference posters, papers, or proceedings?
    • government reports?
    • clinical trials?
  • Who would publish this type of information?
    • government?
    • advocacy groups?
    • academia?
    • industry?
  • Do you have limits to time period or geographic area that you are looking for?

Select keyword search terms for your topic

  1. Choose words that represent the key concepts of your research topic or question
  2. Use a thesaurus or dictionary to find synonyms
  3. Create a search string using Boolean Operators:
  • Group synonyms with brackets using OR to connect them
  • Use AND operator to search multiple ideas and/or phrases
  • Use the truncation symbol * (asterisk) to replace word endings or variant spellings, ie: enviro*
  • Use quotation marks to ensure that words are searched together as a phrase

For example: (your topic) AND (meeting* OR abstract* OR poster* OR conference* OR proceeding* OR congress* OR symposi* OR workshop* OR seminar*)

    4.  Locate key authors  - where and how?

  • Google: look through first 5-10 pages for relevant authorities, organizations or stakeholders. Look at who publishes and/or stores relevant documents. YES you can try contacting these experts.
  • Academic networking
  • Listservs
  • Blogs (blog searching engine)
  • Podcasts

Use Cited Reference Searching
Scanning reference lists ‘snowballing,’ bibliographies and academic CVs.

Keeping Track of your Searches

  • Identify and record the sources you will search. The sources you search will be informed by your research question and where you expect to find information related to your question.
  • Document where you are searching and your search strategies, including document resource name, URL, search terms, and date searched.
  • Collect citation information as you go.
  • Adhere to your established inclusion and exclusion criteria when selecting sources.

An electronic form is another good way of keeping track provided by the following universities:

Start with an OMNI the search engine on the library home page

  • Narrow down results by resource type - see Examples of grey literature in the first section - What is Grey Literature

Many databases allow you to limit your search by content/resource type.  Check individual databases to see if yours do: Databases or Databases by Subject

Explore the following databases:

  • Google Scholar 
    • use "advanced search" options to narrow down your search
    •  limit to title
      “Our findings show that GS results contain moderate amounts of grey literature,with the majority found on average at page 80...We recommend that searches of article titles focus on the first 200 to 300 results.”

      Haddaway NR, Collins AM, Coughlin D, Kirk S. The Role of Google Scholar in Evidence Reviews and Its Applicability to Grey Literature Searching. PLoS One. 2015 Sep 17;10(9):e0138237. doi: 10.1371/journal.pone.0138237

  • Google Think tanks (custom search engine)
  • Google News
  • Google Alerts (set up alerts that cover your topic or follow specific institutions)
  • Google Advanced
    • restricting content to file type 
      • type in your topic and then "filetype:pdf" or "filetype:doc"
    • restricting content to site .org or .gov sites
      • type in your topic and then either "" OR "" 
    • restricting content to searching titles only
      • type search "intitle: "climate change""
    • to exclude words from your search
      • to do this search use operator "-" (minus) eg. jaguar speed -car
    • Search for sites that link to site of interest:

      • link 

    • Find quick information about a site:


    • Search for words in a URL:


        • use Google Australia, Google UK, etc.
        • truncation/wildcard searching is not supported
        • Google & Google Scholar show only the first 1000 results
        • nesting terms in parentheses- eg. (science OR technology) AND (Ontario OR Alberta) - does not work as it does in other databases
  • Use Social media (often organizations and individuals make information about their publications available via social media, alternative yet authoritative literature and informing source)
  • Use other search engines to get broader results. For example, Duck Duck Go does not collect user information and therefore results are not filtered based on your personal profile.

Clinical Trials


Dissertations and Theses

Government Documents

Institutional Repositories

Market Reports

Newspapers and Magazines

While the information in newspapers and magazines might not be acceptable as a source of scientific evidence, they can often point you to key references or provide a source of evidence for public opinion. 


Search Repositories


Content last reviewed: April 15, 2021