Cope, E.D. (1877)
Descriptions of extinct Vertebrata from the Permian and Triassic formations of the United States. Proceedings of the American Philosophical Society, 17, 182–193
Cope, E.D. (1888)
Systematic catalogue of the species of Vertebrata found in the beds of the Permian epoch in North America, with notes and descriptions. Transactions of the American Philosophical Society, 16, 285–297