Morphology of the ovotestis of (Holothurioidea, Apoda): An evolutionary model of oogenesis and the origin of egg polarity in echinodermsDOI: info:10.2307/3226941v. 115No. 146–66
Frick, Jennifer E., Ruppert, Edward E., and Wourms, John P. 1996. "Morphology of the ovotestis of Synaptula hydriformis (Holothurioidea, Apoda): An evolutionary model of oogenesis and the origin of egg polarity in echinoderms." Invertebrate Biology, 115, (1) 46–66. https://doi.org/10.2307/3226941.