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2. Vitamin A content of alfalfa hay;Bethke;Ohio Agr. Exp. Sta. Bul.,1929
3. Studies on changes in vitamin content of alfalfa;Douglass;Col. Agr. Exp. Sta. Tech. Bul.,1933
4. The vitamin A requirements of dairy cows;Fraps;Tex. Agr. Exp. Sta. Bul.,1934
5. Vitamin A content of foods and feeds;Fraps;Tex. Agr. Exp. Sta. Bul.,1933