References
- Hagan , W. A. 1947 . The Infections Diseases of Domestic Animals , Ithaca, N.Y. : Comstock Publishing Co. Inc. .
- Hayes , F. A. and Jordan , H. E. 1956 . J. Amer. vet. med. Ass. , 126 : 161 – 161 .
- Norgarin , S. 1957 . Veterinaria Milano , 6 : 201 – 201 .