Grey literature refers to research that is not published by academic journals or traditional commercial publishers. Some popular examples are government/committee reports, government policies, Hansard, submissions to inquiries, research reports, working papers, guidelines, procedures, conference proceedings, and fact sheets.
Google and Google Advanced Search are effective tools for finding grey literature. Apply search limits to filter for materials of significant quality and better suit the research focus. For example: limit to a site/domain (.gov or .gov.au), limit to pdf file type as one of the most popular report/paper format (.pdf).