1. Brock, W. E., Kleiwer, I. O., &Pearson, C. C. (1965).Journal of the American Veterinary Medical Association,147, 948–951.
2. Dennis, R. A., O'Hara, P. J., Young, M. F., &Dorris, K. D. (1970).Journal of the American Veterinary Medical Association,165, 1861–1869.
3. Kuttler, K. L. (1966).American Journal of Veterinary Research,27, 941–946.
4. Kuttler, K. L. (1967a).Research in Veterinary Science,8, 207–211.
5. Kuttler, K. L. (1967b).Research in Veterinary Science,8, 467–471.