Pham Hung Cuong 2011 Inter-calibration of the ultimate biogas production determined with three different batch fermentation techniques Workshop on Reducing Greenhouse Gas Emissions from Livestock and Soils (Editors: Reg Preston and Sisomphone Southavong). National Institute of Animal Science, Hanoi, 14-15 November 2011. httm://www.mekarn.org/workshops/GHG-CC/pham.nias.htm