Chopra, Isha, and Sushil Chabra. “A Comparative Study of 0.15% Bupivacaine With Tramadol and 0.15% Ropivacaine With Tramadol for Epidural Labour Analgesia”. GMC Patiala Journal of Research and Medical Education, vol. 5, no. 01, June 2022, pp. 38-42, doi:10.56412/gmcp.2022.5.01.93.