Islam, M.S. et al. 2014. Caudal tramadol bupivacaine combination for postoperative pain releif in subumbilical paediatric surgery. Journal of the Bangladesh Society of Anaesthesiologists. 23, 2 (Mar. 2014), 42–46. DOI:https://doi.org/10.3329/jbsa.v23i2.18172.