Katoch, Madan lal, and Loveleen Kour. 2020. “Retracted: Comparative Evaluation of Post-Operative Analgesic Effects of Intraperitoneal Levobupivacaine Plus Fentanyl and Levobupivacaine Plus Tramadol in Patients Undergoing Laparoscopic Cholecystectomy”. International Journal of Clinical Trials 7 (1):28-31. https://doi.org/10.18203/2349-3259.ijct20200203.