Tran Hoang Chat, Ngo Tien Dung, Dinh Van Binh and Preston T R 2005: Effect on yield and composition of water spinach (Ipomoea aquatica), and on soil fertility, of fertilization with worm compost or urea. Livestock Research for Rural Development. Volume 17, Article #108. Retrieved , from http://www.lrrd.org/lrrd17/10/chat17108.htm