1. Morse, E. W. 1910 The ancestry of domesticated cattle. 27th Annual Report, Bureau of Animal Industry.
2. Holstein-Friesian Association of America 1928 Rules and Regulations for the Conduct of Official and Semi-official Tests.
3. A study of the relative reliability of Official Tests for Dairy Cows;Yapp;Ill. Agr. Exp. Sta. Bul.,1919
4. Accuracy of one-day and two-day tests;Petersen;The Jersey Bulletin and Dairy World,1925
5. McDowell, J. C. 1927 Testing cows for production every other month. U. S. D. A. Cir. No. 1, August, 1927.