1. G. Reverberi, Ctenophores, in: “Experimental Embryology of Marine and Fresh-water Invertebrates,” North-Holland Publ., Amsterdam (1971).
2. H. Dunlap, Ctenophora in: “Reproduction in Marine Invertebrates,” Giese, and Pearse ed., Acad. Press. New York, (1974).
3. G. Freeman, The establishment of the oral-aboral axis in the ctenophore embryo, J. Embryol. Exp. Morphol., 42: 237 (1974).
4. M. Strathmann, “Reproduction and Development of Marine Invertebrates of the North Pacific Coast,” University Washington Press (1987).
5. G.R. Harbison, On the classification and evolution of ctenophora in: “The origin and relationship of lower invertebrates,” S. Conway Morris, J.D. George, R. Gilson, and H.M. Platt, ed., Clarendon Press, London (1985).