Songsak Chumpawadee, Kritapon Sommart, Thevin Vongpralub, and Virote Pattarajinda, “Nutritional Evaluation of Energy Feed Sources for Ruminant Using In Vitro Gas Production Technique”, Agr. Nat. Resour., vol. 40, no. 2, pp. 430–435, Apr. 2006.