Pérez-Ramos, Olivia, and Merlynd Nestell. “Permian Fusulinids from Cobachi, Central Sonora, Mexico”. Revista Mexicana De Ciencias Geológicas, vol. 19, no. 1, June 2018, pp. 25-37, https://rmcg.unam.mx/index.php/rmcg/article/view/983.