Preston, 1987. Proceedings of the XXII International Dairy Congress: The Hague 29 September - 30 October 1986, pp. 585-594. D. Reidel Publishing Company, Dordrecht, The Netherlands

Preston, T. R., 1987. Supplementation of tropical feeds. Proceedings of the XXII International Dairy Congress: The Hague 29 September - 30 October 1986, pp. 585-594. D. Reidel Publishing Company, Dordrecht, The Netherlands