1. Utilization of urea by milking cows;Balch;J. Dairy Res.,1961
2. The value of urea as a substitute for the protein in the rations of dairy cattle;Bartlett;J. Agr. Sci.,1947
3. The amino acid handbook;Block,1956
4. Some new concepts of protein nutrition of feedlot cattle (Metabolizable protein and metabolizable amino acids);Burroughs;Vet. Med. Small Anim. Clin.,1971
5. Burroughs, W., A. H. Trenkle, and R. L. Vetter. 1972. Proposed new system of evaluating protein nutrition of feedlot cattle (Metabolizable protein and urea fermentation potential [UFP] of feeds). Iowa State Univ. Coop. Ext. Serv. Leaflet EC-777i.