1. Abramoff, P., Darnell, R. M., Balsano, J. S.: Electrophoretic demonstration of the hybrid origin of the gynogenetic teleost Poecilia formosa. Amer. Naturalist 102, 555?558 (1968).
2. Andrew, W.: Comparative hematology, p. 69?90. New York: Grune and Stratton 1965.
3. Backmann, K., Cowden, R. R.: Specific DNA amounts and nuclear size in fish hepatocytes and erythrocytes. Trans. Amer. micr. Soc. 86, 463?471 (1967).
4. Balsano, J. S.: Systematic relations of fishes of the genus Poecilia in eastern Mexico based upon plasma protein electrophoresis. Ph. D. thesis, 86 pp. Milwaukee, Wisconsin: Marquette University 1968.
5. Boivin, A., Vendrely, R., Vendrely, C.: L'acide d�oxyribonucl�ique du noyau cellulaire d�positaire des caract�res h�r�ditaires; arguments d'ordre analytique. C. R. Acad. Sci. (Paris) 226, 1061?1063 (1948).