"Grey Literature is a field in library and Information science that deals with the production, distribution, and access to multiple document types 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 International (http://www.greynet.org/).
Specifically, grey literature includes things like government publications; reports from universities or corporations; professional organizations, associations, and societies; or nonprofit agencies that aren't published in the usual places, like databases or indexes. Grey literature can be found in print or electronic form.
|Technical reports||Pre-Prints||Fact Sheets|
|Committee reports||Business documents||Newsletters|
|Government documents||Technical documentation||Conference proceedings|
For more information about grey literature, try the IL Toolkit - Finding Information by the University of Arizona.
The following can be useful in locating grey literature in the medical, public health, and psychology fields: