Canadian Agency for Drugs and Technology in Health's (CADTH) free online resource for grey literature searching, “Grey Matters: a practical tool for searching health-related grey literature.”
Grey Matters: a practical tool for searching health-related grey literature (Word Document available for download)
Think tanks are a source for policy research but make sure you look at the "about page" and Board to read their mandate and mission. Do they receive funding and if they do from who?
UBC Subscription Policy Databases
U.S. / International
Grey Literature is "literature produced on all levels of government, academics, business, and organization in electronic and print formats not controlled by commercial publishing i.e. where publishing is not the primary activity of the producing body" Greynet.
Examples of grey literature include:
Grey literature can be difficult to find because: