Campos Filho, Olívio Ribeiro, et al. “Erosion and Runoff Rates on an Alfisol in Northeastern Brazil”. Pesquisa Agropecuaria Brasileira, vol. 26, no. 7, July 1991, pp. 1057-62, doi:10.1590/S1678-3921.pab1991.v26.3439.