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
NEWBERRY, J.S. & WORTHEN, A.H. (1870)
Geology and Palaeontology. Descriptions of fossil vertebrates. Geological Survey of Illinois, 4: 343–374