Grey literature is materials and research produced by organizations outside of the traditional commercial or academic publishing and distribution channels.
Common grey literature publication types include reports (annual, research, technical, project, etc.), working papers, government documents, white papers and evaluations.
Organizations that produce grey literature include government departments and agencies, civil society or non-governmental organizations, academic centers and departments, and private companies and consultants.
Grey literature may often be found in the usual sources that you are searching, such as subject databases, Worldcat, JSTOR, and the Open Access section in the UNO Library catalog.
If you are in Google or Google Scholar try utilizing search terms for the type of resource you need, for example:
Below are a few other sources: