Hoeh, W.R., K.S. Frazer, E. Naranjo-Garcia & R.J. Trdan. 1995. A phylogenetic perspective on the evolution of simultaneous hermaphroditism in a freshwater mussel clade (Bivalvia: Unionidae: Utterbackia). Malacological Review 28: 25-42.
(click the figure number to see the cladogram)