FAN , Yunxia; JI , Muhuo; ZANG , Lina; WANG , Wenhui; YIN , Qi; XU , Jian; YANG , Jianjun. Comparison of epidural tramadol-ropivacaine and fentanyl-ropivacaine for labor analgesia: A prospective randomized study. Upsala Journal of Medical Sciences, [S. l.], v. 116, n. 4, p. 252–257, 2011. DOI: 10.3109/03009734.2011.601532. Disponível em: https://ujms.net/index.php/ujms/article/view/6059. Acesso em: 14 nov. 2026.