Young, A. M., and A. Muyshondt. “Geographical and Ecological Expansion in Tropical Butterflies of the Genus <i>Morpho</i> In Evolutionary Time”. Revista De Biología Tropical, vol. 20, no. 2, Dec. 1972, pp. 231–263, https://revistas.ucr.ac.cr/index.php/rbt/article/view/27483.