Chhay T, Vor S, Borin K and Preston T R 2013: Effect of different levels of biochar on the yield and nutritive value of Celery cabbage (Brassica chinensis var), Chinese cabbage (Brassica pekinensis), Mustard green (Brassica juncea) and Water spinach (Ipomoea aquatica). Livestock Research for Rural Development. Volume 25, Article #8. Retrieved , from http://www.lrrd.org/lrrd25/1/chha25008.htm