OLIVEIRA, Manoel Rivelino Gomes de, et al. “STATISTICAL ANALYSIS OF THE RUNOFF COEFFICIENT IN THE WATERSHED SEMIARID ENVIRONMENT”. Brazilian Journal of Biometrics, vol. 33, no. 3, Oct. 2015, pp. 277-90, http://www.cienciadainformacaoexpress.ufla.br/index.php/BBJ/article/view/15.