Grey literature refers to both published and unpublished research material that is not available commercially. It is often of a scientific or technical nature and is not available through the usual bibliographic sources, such as databases or indexes.
It is produced by government departments, universities, corporations, associations and societies, and professional organisations.
Grey literature, due to its diverse origins and unpublished nature, can be difficult to find. It is often found by searching for the agency or institution who is most likely to produce the literature. The search may require looking at a large number of sources.
Here are a few places to start looking:
Searching the online catalogue of large libraries for grey literature can be fruitful.
Academic conferences are events where people present news about their recent research and findings. Many conferences are held annually, sometimes at a different location each year. The conference organisers often collect the presented papers and publish them as the conference proceedings.
Contacting authors, peer groups and private companies can sometimes be a way of tracking down difficult to find grey literature. This can be done through:
Theses often contain cutting-edge material. In many cases the information may not have made its way into published journal articles or books.
Since there are two accepted spellings, to locate information on gray/grey literature in general, search for: (gray OR grey) literature.
Most of the grey literature available on the Web is in the form of PDF documents so can save time by typing filetype:pdf after your keywords. Also consider restricting your search to the .org and/or .gov domains, e.g. type site:org after your search terms.
Grey literature is an important source of information. To carry out a thorough search of the literature in your area it is essential to search for material which has not been published through commercial channels.
Though not always scholarly, it is produced by researchers and practitioners in the field. This may give you additional insight into working practice or allow you to develop current awareness from a non academic point of view.
It can often be produced more quickly, therefore being more current than other types of literature that have to go through a more formal review process. It may also be reporting on work in progress, for example conference literature may reflect ongoing research. This does mean that grey literature need additional scrutiny.
In addition, it can reduce positive publication bias - negative results are often reported in the grey literature but not in published work.