1. Binnerts W.T., A.T. Van Klooster, and A.M. Frens. 1968. Soluble chromium indicator measured by atomic absorption in digestive experiments. Vet. Rec. 82: 470
2. Bergman, E.N., R.S. Reid, M.G. Murray, J.M. Brockway, and F.G. Whitelaw. 1965. Interconversions and production of volatile fatty acids in the sheep rumen. Biochem. J. 97: 5–58
3. Boadi, D.A., K.M. Wittenberg, and A.D. Kennedy. 2002. Validation of the sulphur hexafluoride (SF6) tracer gas technique for measurement of methane and carbon dioxide production by cattle. Can. J. Anim. Sci. 82:125–131
4. Blake, J.S., D.N. Salter, and R.H. Smith. 1983. Incorporation of nitrogen into rumen bacterial fractions of steers given protein-and urea-containing diets. Ammonia assimilation into intracellular bacterial amino acids. Br. J. Nutr. 50:769–782
5. Czerkawski, J.W. 1986. An introduction to rumen studies. Pergamon Press, Oxford