James L. Murphy, "The Ohio Diamond Mine-- Paleontological Treasure Trove," Echoes 19, no. 2 (February 1980): 4-5.
Abstract:
The history of the Diamond coal mine near Linton P.O., Jefferson Co., Ohio, and the famous Pennsylvanian-age vertebrate fauna associated with it is outlined. A previously undocumented example of the amphibian genus Ptyonius is illustrated.