Carranza, S.; Littlewood, D. T. J.; Clough, K. A.; Ruiz-Trillo, I.; Baguna, J.; Riutort, M. (1998). A robust molecular phylogeny of the Tricladida (Platyhelminthes: Seriata) with a discussion on morphological synapomorphies. Proc Roy Soc Lond B, 265: 631-640