Tran Hiep, Dang Vu Hoa and Nguyen Xuan Trach 2012  Mitigation of methane emission by means of oil and nitrate supplement in diets of growing cattle.  Proceedings of the International Conference "Livestock-Based Farming Systems, Renewable  Resources and the Environment", 6-9 June 2012, Dalat, Vietnam (Editors: Reg Preston and Sisomphone Southavong) http:/www.mekarn.org/workshops/dalat2012/html/hiep.hua.htm