Grey literature refers to texts not published through traditional academic or commercial channels. 

Among other works, grey literature includes white papers, position statements, working papers, manuscripts, professional conference presentations, and various governmental and nongovernmental publications.  Observers have referred to grey literature alternately as fugitive literature, non-conventional literature, and ephemeral publications. 

Never published in "black and white" like scholarly articles or books, these texts often prove more difficult to locate, organize, and preserve.  As a result, grey literature tends to be more elusive and ephemeral than traditional information resources.

Thanks to the efforts of government document librarians, public policy librarians, and other information professionals, the researcher now has at her disposal a range of grey literature finding aids, databases, and bibliographies.  The following sections collect many of these resources.  

Because white papers, policy reports, and other grey literature exist outside the academic publication ecosystem, they rarely are subjected to peer review. 

Similarly, the authors of academic working papers, manuscripts, and conference presentations eventually may submit these texts for publication in refereed journals, but these works have not yet been appraised for quality.  As a result, it may more difficult to determine the credibility of grey literature than it is for traditional academic publications.  Under these conditions, authorial--individual, organizational, etc.--reputation tends to assume greater significance.  The following resources address the question of credibility, especially as it concerns think tanks.