1. M. V. Krylov and V. I. Zaionts, Zhivotnovodstvo, No. 4, 27 (1974).
2. I. A. Koblova and V. B. Piskov, Khim. Sel'sk. Khoz., No. 1, 40 (1972).
3. M. V. Krylov and V. I. Zaionts, Veterinariya, No. 8, 76 (1972).
4. V. I. Zajonc, Vet. Spofa.,15, No. 2, 115 (1973).
5. L. Kowalski and M. W. Reid, J. Parasitol.,56, No. 4, 279 (1970).