1. The Nutrient Requirements of Ruminant Livestock;Agricultural Research Council,1980
2. The Nutrient Requirements of Ruminant Livestock;Agricultural Research Council,1984
3. Problems in predicting the value of non-protein nitrogen as a substitute for protein in rations of farm ruminants;Balch;World Rev. Anim. Prod.,1967
4. The effect of live weight and energy intake on nitrogen requirements of lambs;Black;Br. J. Nutr.,1975
5. Energy Metabolism in Animals and Man;Blaxter,1989