Zilli, J. Édson et al. 2006. Symbiotic efficiency of cowpea <i>Bradyrhizobium</i> strains in Cerrado soils. Pesquisa Agropecuaria Brasileira. 41, 5 (May 2006), 811–818. DOI:https://doi.org/10.1590/S1678-3921.pab2006.v41.7210.