Dr. K. Selvarju and N.Naveen Kumar (2018) “A comparative study of intrathecal clonidine and intrathecal tramadol for prolongation of neuraxial blockade analgesia with 0.5% bupivacaine in orthopaedic surgery”, Asian Pacific Journal of Health Sciences, 5(3), pp. 117–124. doi: 10.21276/apjhs.2018.5.3.17.