1. Cobban, W. A., 2016, A survey of the Cretaceous ammonite Placenticeras Meek, 1876, in the United States Western Interior, with notes on the earliest species from Texas: Acta Geologica Polonica, v. 66, p. 587-608.
2. Kennedy, W. J., Cobban, W. A., and Landman, N. H., 1996, Two species of Placenticeras (Ammonitina) from the Upper Cretaceous (Campanian) of the Western Interior of the United States: American Museum Novitates, no. 3173, 13 p.
3. Larson, N. L., Jorgensen, S. D., Farrar, R. A. and Larson, P. L., 1997, Ammonites and the other cephalopods of the Pierre Seaway: Tucson, AZ, Geoscience Press, 148 p.