Souza, A. A. de; Burity, H. A.; Figueiredo, M. do V. B.; Silva, M. L. R. B. da; Melotto, M.; Tsai, S. M. Symbiotic Efficiency of Hup+, Huphr and Hup- Bradyrhizobium Japonicum and Bradyrhizobium Elkanii Strains in Cowpea Cultivars. PAB 1999, 34 (10), 1925-1931. https://doi.org/10.1590/S1678-3921.pab1999.v34.5518.