1. The best week in a cow's lactation period;Haecker;Nebraska Agr. Exp. Sta. Bul.,1903
2. Studies in dairy production;Woll;Wis. Agr. Exp. Sta. Res. Bul.,1912
3. Grady, R. I. 1917 Stage of lactation affects milk yield. Ohio Monthly Bul., ii, no. 12.
4. Summary of three state dairy cow competitions;Woll;Hoard's Dairyman,1923