1. Fenner, F., The Biology of Animal Viruses, 1, 375 (Academic Press, New York, 1968).
2. Fenner, F., The Biology of Animal Viruses, 2, 475 (Academic Press, New York, 1968).
3. Cooper, P. D., and Bellett, A. J. D., J. Gen. Microbiol., 21, 485 (1959).
4. Henle, W., J. Immunol., 91, 145 (1963).
5. Baron, S., Medical Virology, 1, 77 (1967).