1. Hagen, W. A., and Brunner, D. W., The Infectious Diseases of Domestic Animals, third ed., 251 (Comstock Publishing Company, Ithaca, New York, 1957).
2. Hull, Thomas C., Diseases Transmitted from Animals to Man, fifth ed., 143 (C. C. Thomas, Springfield, Illinois, 1963).
3. Lombardini, F., personal communication (1962).