Dunbar, C. O. (1944). Permian and Pennsylvanian (?) fusulines, Part II of Geology and Paleontology of the Permian Area Northwest of Las Delicias, Southwestern Coahuila, Mexico. Geological Society of America Special Papers. 52: 35-48.
Permian and Pennsylvanian (?) fusulines, Part II of Geology and Paleontology of the Permian Area Northwest of Las Delicias, Southwestern Coahuila, Mexico