Araújo, F.F. de and Hungria, M. (1999) “Soybean nodulation and yield when co-inoculated with Bacillus subtilis and Bradyrhizobium japonicum / bradyrhizobium elkanii”, Pesquisa Agropecuaria Brasileira, 34(9), pp. 1633–1643. doi:10.1590/S1678-3921.pab1999.v34.5420.