Costa, Newton de Lucena. 1995. “Nitrogen Fertilization and Association of Elephant-Grass (Pennisetum Purpureum Cv. Cameroon) With Tropical Forage Legumes”. Pesquisa Agropecuaria Brasileira 30 (3): 401-8. https://doi.org/10.1590/S1678-3921.pab1995.v30.4321.