Kaniyil, Suvarna, and Priya Radhakrishnan. “Does Fentanyl Prolong the Analgesia of Local Anaesthetics in Brachial Plexus Block? A Randomized Controlled Study”. International Journal of Research in Medical Sciences 5, no. 2 (January 23, 2017): 583–587. Accessed October 9, 2025. https://www.msjonline.org/index.php/ijrms/article/view/2280.