Carvalho, André Vieira de, et al. “Response of African Oil Palm to Nitrogen Addition and Its Influence on the Diazotrophic Bacteria Population”. Pesquisa Agropecuaria Brasileira, vol. 41, no. 2, Feb. 2006, pp. 293-00, doi:10.1590/S1678-3921.pab2006.v41.7136.