Etayo Serna, Fernando. “Faunas Position in the Colombian Cretaceous Deposits and Their Value in Their Chronological Subdivision”. Boletín de Geología, no. 16-17 (June 23, 1964): 5–142. Accessed May 17, 2024. https://revistas.uis.edu.co/index.php/revistaboletindegeologia/article/view/5783.