Saxena, D., Sanwatsarkar, S., Dixit, A. and Arya, B. (2017) “Comparative study of duration of analgesia with epidural bupivacaine and bupivacaine with tramadol in lower limb surgeries”, International Journal of Research in Medical Sciences, 5(5), pp. 2003–2010. doi: 10.18203/2320-6012.ijrms20171833.