CHANDNANI, K.; SAINEE, H. B. Pain relief in labour: tramadol versus pentazocine. International Journal of Reproduction, Contraception, Obstetrics and Gynecology, [S. l.], v. 2, n. 2, p. 186–189, 2016. Disponível em: https://www.ijrcog.org/index.php/ijrcog/article/view/207. Acesso em: 28 oct. 2025.