Duong Nguyen Khang and Preston T R 2005: Effect of  effluent from low-cost plastic film biodigester on yield and chemical composition of cassava foliage and tuber yield.  Workshop-seminar "Making better  use of local feed resources" (Editors: Reg Preston and Brian Ogle) MEKARN-CTU, Cantho, 23-25 May, 2005. Article #6. Retrieved, from http://www.mekarn.org/proctu/khan6.htm