1. Illinois Agriculture Experiment Station Bulletin 1897 46
2. Michigan Experiment Station Quarterly Bulletin 1928 11 1
3. Johnson, P. E., Journal of Dairy Science 23: 553 (1940).
4. McCandlish, A. C., Journal of Dairy Science 6: 54 (1923).
5. Mead, S. W., Journal of Dairy Science 19: 465 (1936).