1. Valembois, P., C. R. Acad. Sci., Paris, 257: 3489–3490 (1963).
2. Duprat, P., C. R. Acad. Sci., Paris, 259: 4177–4180 (1964).
3. Cooper, E. L., Am. Zool., 5: 254 (1965).
4. Cooper, E. L., J. Exptl. Zool., 171: 69–73 (1969a).
5. Cooper, E. L. and Rubilotta, L. M., Transplantation, 8: 220–223 (1969).