Grey literature is information that is not controlled by commercial publishing. It is produced on all levels of government, academia, NGOs, associations and professional organizations and is available in electronic and print formats.
Grey literature is not easily found. It is often excluded from large databases and other mainstream sources.
Use grey literature to complement your search.
There are many types of grey literature ranging from more scholarly to more community based kinds of grey literature.
For example: Theses and dissertations, conference proceedings and research reports are scholarly kinds of grey literature. Association websites, newsletters, e-mails, blogs and other social networking sites are community based kinds of grey literature.