Zur Morphologie sublitoraler Otoplanidae (Turbellaria, Proseriata) von Helgoland und Neapel. [On the morphology of sublittoral Otoplanidae (Turbellaria, Proseriata) from Helogoland and Naples.] - Ax, P.; Weidemann, E.; Ehlers, B. (Zoomorphologie, 1978)