Castillo, R. C., S. Ramos, J. Nieto-Obregon, and E. Gonzalez-Partida. “Carbon Isotopic Analysis in Mexico: A Progress Report on Some Mexican Ore Deposits and Metamorphic Rocks”. Geofisica Internacional 27, no. 1 (January 1, 1988): 149–157. Accessed May 17, 2024. http://revistagi.geofisica.unam.mx/index.php/RGI/article/view/1121.