Kaniyil S, Radhakrishnan P. Does fentanyl prolong the analgesia of local anaesthetics in brachial plexus block? A randomized controlled study. Int J Res Med Sci [Internet]. 2017 Jan. 23 [cited 2025 Oct. 9];5(2):583-7. Available from: https://www.msjonline.org/index.php/ijrms/article/view/2280