Silva, V.N. da et al. (2007) “CHARACTERIZATION AND SELECTION OF NATIVE POPULATIONS OF SOIL RHIZOBIA OF THE SEMI-ARID REGION OF PERNAMBUCO, BRAZIL”, Pesquisa Agropecuária Tropical [Agricultural Research in the Tropics], 37(1), pp. 16–21. doi:10.5216/pat.v37i1.1841.