1. R. Reinboth, Zool. Anz., suppl.24, 259 (1961).
2. S.T.H. Chan, Phil. Trans. R. Soc. Lond. B259, 59 (1970).
3. S.T.H. Chan, W.S.O. and W.B. Hui, in: Intersexuality in the animal kingdom, p. 201. Ed. R. Reinboth, Springer, Heidelberg 1974.
4. S.T.H. Chan, Handbook of sexology, p. 91. Eds J. Money and H. Musaph, Elsevier/North-Holland Biomedical Press Amsterdam 1977.
5. L. Fishelson, in: Intersexuality in the animal kingdom, p. 284. Ed. R. Reinboth. Springer, Heidelberg 1974.