Ruschel, A.P. et al. 2014. Influence of mineral and organic nitrogen on symbiotic fixation of nitrogen by soybeans. Pesquisa Agropecuaria Brasileira. 9, 10 (Apr. 2014), 125–129. DOI:https://doi.org/10.1590/S1678-3921.pab1974.v9.17271.