Carvalho, A. V. de, Alves, B. J. R. and Reis, V. M. (2006) “Response of African oil palm to nitrogen addition and its influence on the diazotrophic bacteria population”, Pesquisa Agropecuaria Brasileira, 41(2), pp. 293–300. doi: 10.1590/S1678-3921.pab2006.v41.7136.