1. Ely and Petersen, J. Dairy Sci., 17 (1937).
2. Grachev, P. I., Zh. Obsh. Biol. (U.S.S.R.), 14, 333 (1953).
3. Barishnikov, I. A., Borsuk, V. N., Zax, M. G., Zotikova, I. N., Pavlov, G. N., and Tolbukhin, V. I., Zh. Obsh. Biol. (U.S.S.R.), 14, 257 (1953).