“Comparison of epidural Ropivacaine 0.75% and Ropivacaine 0.75% Plus Buprenorphine (0.5 ml) for total knee replacement surgery”, Int J of Biomed & Adv Res, vol. 8, no. 6, pp. 244–249, Jun. 2017, doi: 10.7439/ijbar.v8i6.4259.