Mathew, L. M., L. Mathew, V. Cherian, and A. David. “Effect of Epidural Ketamine on Pain After Total Knee Arthroplasty: A Randomized Double- Blind Placebo Controlled Clinical Trial”. Christian Journal for Global Health, Vol. 9, no. 1, June 2022, pp. 77-86, doi:10.15566/cjgh.v9i1.641.