1. Jackson, H., and Bock, M., Nature, 175, 1073 (1955).
2. Fahmy, O. G., and Fahmy, M. J., J. Genet., 52, 603 (1954).
3. Fahmy, O. G., and Fahmy, M. J., J. Genet., 53, 603 (1955).
4. Hertwig, P., Z. indukt. Abstammungs-u. Vererbungslehre, 71, 1 (1940).
5. Snell, G. D., Genetics, 20, 247 (1935).