Grey literature are materials and research produced by organizations outside of the traditional commercial or academic publishing and distribution channels.
Grey literature stands for manifold document types produced on all levels of government, academics, business and industry in print and electronic formats that are protected by intellectual property rights, of sufficient quality to be collected and preserved by libraries and institutional repositories, but not controlled by commercial publishers; i.e. where publishing is not the primary activity of the producing body.
Examples of grey literature in the Health field for instance, include: