Phuong L T B, Preston T R and Leng R A 2012: Effect of foliage from “sweet” and “bitter” cassava varieties on methane production in in vitro incubation with molasses supplemented with potassium nitrate or urea. Livestock Research for Rural Development. Volume 24, Article #189. Retrieved , from http://www.lrrd.org/lrrd24/10/phuo24189.htm