Grey literature covers a wide range of information published or produced by various sources e.g. heath institutes, international agencies, non-profit organisations, professional bodies and local and national government.
Examples of grey literature include (but are not limited to):
Searching for grey literature does require time and effort. These types of sources may not be surfaced within a library catalogue or subject specific database, but may be found within specific websites responsible for producing or publishing the information. See the Where can I find grey literature section? of this guide for ideas on where to search.