Sour-Tovar, Francisco, Alberto Pérez-Huerta, Sara A. Quiroz-Barroso, and Elena Centeno-García. “Lower Permian Brachiopods and Trilobite from Northwerstern Hidalgo State, Mexico”. Revista Mexicana de Ciencias Geológicas 22, no. 1 (April 25, 2018): 24–35. Accessed March 15, 2025. https://rmcg.unam.mx/index.php/rmcg/article/view/862.