That which is produced on all levels of government, academics, business and industry in print and electronic formats, but which is not controlled by commercial publishers.
From Grey Literature Report (Grey Literature Report). Accessed August 20, 2015.
Grey literature sources may be the only information available on certain topics and in certain contexts. Incorporating a structured grey literature search and resources in your projects and research may minimize publication or reporting bias. Grey literature findings may counteract the tendency toward exaggerated effectiveness of therapeutic interventions often found in traditionally published literature (which tends to have positive findings).