Grey Literature is "[i]nformation produced on all levels of government, academics, business and industry in electronic and print formats not controlled by commercial publishing i.e. where publishing is not the primary activity of the producing body." (http://greynet.org/)
Grey Literature includes:
(http://lanic.utexas.edu/project/laoap/glossary.html)
Some common places to find Grey Literature:
A large amount of of grey literature can be found if the information is available on the internet. The issue is finding these sources. Despite the potency of search engines such as Google, Yahoo and Bing, these tools do not cover the entirety of the web. Many of the resources can be found in a hidden web, often referred to as the "Deep Web."
The Deep Web is composed of searchable databases accessible through the internet, which are not availabe through ordinary web search engines. It is also called the "hidden web" or "invisible web." (Retrieved from http://www.credoreference.com/entry/acbinfomanage/deep_web.)
Deep Web Tools:
A directory is a list of information guiding you to additional resources. Below you will find links to resources that contain large lists of resources of and about grey literature.
An Institutional Repository is a virtual space where an institution (like a university or research institute) collects, preserves and, to a degree, distributes its research and findings. Since these resources are not traditionally published, they can be considered grey literature.
Use the search below to search the top 800 Institutional Repositories (according to http://repositories.webometrics.info/index.html) at once, or search individual repositories via the links further down.