Silva, Jefté Ferreira da, et al. “Genetic Divergence of Cowpea Genotypes for Resistance to Black Aphid”. Pesquisa Agropecuaria Brasileira, vol. 47, no. 7, Aug. 2012, pp. 950-6, doi:10.1590/S1678-3921.pab2012.v47.12071.