Nathaniel Bletter, Douglas C. Daly, "Cacao and its relatives in South America" in Cameron L. McNeil, ed., Chocolate in Mesoamerica: a cultural history of cacao (Gainesville: University Press of Florida, 2006) pp. 31-68
Barbara A. Whitlock, David A. Baum, "Phylogenetic Relationships of Theobroma and Herrania (Sterculiaceae) Based on Sequences of the Nuclear Gene Vicilin" in Systematic Botany vol. 24 (1999) pp. 128-138