Tewari A, Singh AK. Comparative evaluation of caudal tramadol and fentanyl when mixed with bupivacaine in paediatric age group. Int J Res Med Sci [Internet]. 2020 Mar. 26 [cited 2025 Oct. 14];8(4):1445-50. Available from: https://www.msjonline.org/index.php/ijrms/article/view/7829