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Using Grey Literature in your Research: Grey Literature Searches - Overview

A guide to searching and using grey literature

General Advice and Overview

Grey Literature methods overview
Overview of Grey Literature Search Methods

There are no formal guidelines for grey literature searching - the search strategy will need to be tailored to your specific research question. Some general advice:

  • Use a broad and diverse strategy, ideally combining several search methods rather than relying on just one [1, 2, 3]. 
  • Think critically about which grey literature sources are likely to be valuable for your research question (e.g., preprints, dissertations, government reports, etc.).
    • Preliminary searches can help give an idea of which databases and websites are most likely to yield relevant results.
  • Develop a detailed plan before starting your formal search. This plan will provide structure and transparency, and will also help with time management [2].

Documentation

The grey literature search strategy should be documented in the same level of detail as a traditional literature search, following the PRISMA-S checklist.  Each stage of the screening process should also be reported in a PRISMA flow diagram. 

Other tips:

  • Any stopping rules (e.g. screen first X results; screen until Y consecutive irrelevant results) should be decided upon and documented before beginning the search.
  • For each search engine, database, or website searched, keep a record of:
    • All search strings used
    • Any search filters used
    • Date of search
    • Whether results were screened in the browser or exported for later screening.
  • If you are contacting experts in the field to ask for recommended documents or sources (e.g., via mailing lists or personal communication), use a spreadsheet to keep a record of contact attempts, responses, and potential sources uncovered via this mechanism.

Further reading and resources:

1. Adams RJ, Smart P, Huff AS. Shades of Grey: Guidelines for Working with the Grey Literature in Systematic Reviews for Management and Organizational Studies. Int J Manag Rev. 2016;19(4):432-54. [link]

2. Godin K, Stapleton J, Kirkpatrick SI, Hanning RM, Leatherdale ST. Applying systematic review search methods to the grey literature: a case study examining guidelines for school-based breakfast programs in Canada. Syst Rev. 2015;4:138. [link]

3. Mahood Q, Van Eerd D, Irvin E. Searching for grey literature for systematic reviews: challenges and benefits. Res Synth Methods. 2014;5(3):221-34. [link]*

4. Stansfield C, Dickson K, Bangpan M. Exploring issues in the conduct of website searching and other online sources for systematic reviews: how can we be systematic? Syst Rev. 2016;5:9. [link]

5. This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Template adapted from https://guides.library.utoronto.ca/c.php?g=577919&p=4123572 a guide developed by the Gerstein Science Information Centre, University of Toronto Libraries.

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