Dzung Ngo Tien and Preston T R 2007: Effect of increasing area of cassava (Manihot esculenta Crantz) relative to Flemingia (Flemingia macrophylla) on biomass yield, soil fertility and soil erosion. Livestock Research for Rural Development. Volume 19, Article #22. Retrieved , from http://www.lrrd.org/lrrd19/2/dzun19022.htm