Lamba A, Sardana P, Kaur R. Comparison of parenteral tramadol and epidural ropivacaine for labour analgesia: a prospective clinical study. Int J Reprod Contracept Obstet Gynecol [Internet]. 2017 Jan. 5 [cited 2025 Dec. 4];5(6):1722-7. Available from: https://www.ijrcog.org/index.php/ijrcog/article/view/1185