1. Nutrient Requirements of Ruminants;Agricultural Research Council,1980
2. Standard Methods for the Examination of Dairy Products;American Public Health Association,1978
3. Biuret, urea and natural proteins as nitrogen supplements for low quality roughage for sheep;Ammerman;J. Anim. Sci.,1972
4. Official Methods of Analysis;Association of Official Analytical Chemists,1984
5. Silage Fermentation;Barnett,1954