1. Ax, P., 1984. Das phylogenetische System. G. Fischer, Stuttgart, New York, 349 pp.
2. Brooks, D. R., 1989a. A summary of the database pertaining to the phylogeny of the major groups of parasitic platyhelminths, with a revised classification. Can. J. Zool. 67: 714–720.
3. Brooks, D. R., 1989b. The phylogeny of the Cercomeria (Platyhelminthes: Rhabdocoela) and general evolutionary principles. J. Parasitol. 75: 606–616.
4. Brüggemann, J., 1986. Feinstruktur der Protonephridien von Paromalostomum proceracauda (Plathelminthes, Macrostomida). Zoomorphology 106: 147–157.
5. Brüggemann, J., 1989. Ultrastruktur des Exkretionssystems von Vejdovskya pellucida (Plathelminthes, Rhabdocoela). Microfauna Marina 5: 227–242.