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Evidence Synthesis : Grey Literature

Useful resources and tools for planning and conducting systematic reviews

What is Grey Literature?

Grey Literature includes sources that do not fall into "traditional" publishing categories: theses/dissertations, government documents/reports, white papers, patents, conference proceedings, newsletters, unpublished or unfinished clinical trials, etc. 

The 12th International Conference on Grey Literature (Prague, 2010) provided the following definition: 

"Grey literature stands for manifold document types produced on all levels of government, academics, business and industry in print and electronic formats that are protected by intellectual property rights, of sufficient quality to be collected and preserved by libraries and institutional repositories, but not controlled by commercial publishers; i.e. where publishing is not the primary activity of the producing body."

Google & Google Scholar

Using "site searching" can be a useful way of finding grey literature (especially government reports). 

Examples of site searching: 

  • childhood obesity site:.gov (would only retrieve results from .gov sites). 
  • childhood obesity site:nih.gov (would only retrieve results from The National Institutes of Health website)

Other Google resources that could be useful are linked below:

Where to find Grey Literature