Phuong L T B, Khang D N and Preston T R 2015: Methane production in an in vitro fermentation of cassava pulp with urea was reduced by supplementation with leaves from bitter, as opposed to sweet, varieties of cassava. Livestock Research for Rural Development. Volume 27, Article #162. Retrieved , from http://www.lrrd.org/lrrd27/8/phuo27162.html