1. Siewing R: Lehrbuch der vergleichenden Entwicklungsgeschichte der Tieresamburg und Berlin: Paul Parey, 1969
2. Pechenik JA: Biology of the Invertebrates, second edition. Dubuque, IA: Wm. C. Brown Publishers, 1991
3. Kaiser HE: Functional Comparative Histology. 2. Communication: Organismic taxonomy (Plant and animal taxonomy). Gegenbaurs morph Jahrb, Leipzig 131: 643?699, 1985
4. Kaiser HE (ed): Neoplasms ? Comparative Pathology of Growth in Animals, Plants, and Man. Baltimore-London: Williams & Wilkins, 1981
5. Kaiser HE (series ed): Cancer Growth and Progression. Dordrecht-Boston-London: Kluwer Academic Publishers, 1989