Newberry, J.S. & Worthen, A.H. (1866)
Descriptions of new species of vertebrates, mainly from the Sub-Carboniferous Limestome and Coal Measures of Illinois. Geological Survey of Illinois, 2, 9–134
Murphy, J.L. (1971)
A Physonemus Spine from the Lower Mercer Limestone (Pennsylvanian) of Portage County, Ohio. Ohio Journal of Science, 71(4), 240–243