San Thy, Preston T R, Duong Nguyen Khang, Bounthong and Choke Mikled 2005: Effect of length: diameter ratio in polyethylene biodigesters on gas production and effluent composition.  Workshop-seminar "Making better  use of local feed resources" (Editors: Reg Preston and Brian Ogle) MEKARN-CTU, Cantho, 23-25 May, 2005. Article #05. Retrieved, from http://www.mekarn.org/proctu/sant05.htm