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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
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Contributions from Walker Museum. I: The vertebrates from the Permian bone bed of Vermilion County, Illinois. The Journal of Geology, 8(8), 698–729
Hay, O.P. (1902)
Bibliography and catalogue of the fossil Vertebrata of North America. Bulletin of the United States Geological and Geographical Survey of the Territories, 179, 1–868