TEWARI, A.; SINGH, A. K. Comparative evaluation of caudal tramadol and fentanyl when mixed with bupivacaine in paediatric age group. International Journal of Research in Medical Sciences, [S. l.], v. 8, n. 4, p. 1445–1450, 2020. DOI: 10.18203/2320-6012.ijrms20201340. Disponível em: https://www.msjonline.org/index.php/ijrms/article/view/7829. Acesso em: 14 oct. 2025.