Umaña V, G., and C. Jiménez. “The Basic Limnology of a Low Altitnde Tropical Crater Lake: Cerro Chato, Costa Rica”. Revista De Biología Tropical, vol. 43, no. 1-3, Dec. 1995, pp. 131–138, https://revistas.ucr.ac.cr/index.php/rbt/article/view/22421.