Grey literature

The reporting of your grey literature search might not be as straightforward as reporting searches on subscription databases. The results of web searches might not be as reproducible to the same extent as database searches because web content and search algorithms often change. You should keep records of what and when you search and your results in case the website or document is taken down or deleted and aim to record the following information: 

• The name of the website or resource accessed. 
• The web address or URL if available. 
• The date of the search. 
• Keywords used or details of how you searched. 

Although grey literature can be very valuable and useful for your projects, not all grey literature materials go through a formal peer review and editorial process like studies in academic journals and can therefore vary in terms of quality. 

 It is therefore crucial to carefully consider whether the grey literature you are using is trustworthy, reliable and accurate: 

• Authority: Who is the author/source? What are their qualifications? Do they have any expertise in the area?
• Objectivity: Is there bias? How are the claims justified? Is the purpose to promote a product/service?
• Intended audience: Who is the source aimed at? Is it general public or scientific community? 
• Accuracy: Are the facts/figures, dates cited, and quality of evidence reliable and valid? Is the information cited and references included?
• Currency: How up to date is the information? When was it created? Is there more recent information available?

One tool you can use to help with evaluating grey literature, especially in health sciences, is the AACODS Checklist for appraising grey literature

See also our guidance on evaluating academic literature.