Balboa, Oscar, et al. “Incompetence of Esophagie Inferior Sphincter. Their Relation With Intrathoracic and Intraabdominal Pressures”. Cirugía Del Uruguay, vol. 49, no. 6, Mar. 1979, pp. 550-2, https://replica-revista.scu.org.uy/index.php/cir_urug/article/view/3112.