1. Rightsel, W. A., Science 134: 558 (1961).
2. Crowther, D., Virology 15: 65 (1961).
3. Barrera-Oro, J., Texas Reports on Biology and Medicine. 19: 528 (1961).
4. Melnick, J. L., Pan-Am. Sanitary Bur. Scientific Publ. No. 50. : 12 (1960).
5. Dulbecco, R., Pan-Am. Sanitary Bur. Scientific Publ. No. 50. : 47 (1960).