What is "grey Literature"?
Grey literature is the term given to publications produced by government departments, charities, business, industries, etc in short anything that is not produced commercially. It is a great source of authoritative information on quite narrow areas of research. Be careful and apply the normal criteria in establishing the reliability of the publication before you use it.
Where to find grey literature
Ethos - PhDs held in the British Library, great source of research
Pre-print Servers -listed separately in the Libguide -ArXiv is one such example
GreyNet - provides links to sources of information
Social Science Research Network (SSRN) - papers, research, conference papers, etc
The list is not exhaustive and many databases/eResources have grey literature included on them