Moorthy, Soundharya, et al. “COMPARISON OF THE EFFICACY AND SAFETY OF TRAMADOL VERSUS TAPENTADOL IN ACUTE OSTEOARTHRITIC KNEE PAIN: A RANDOMIZED, CONTROLLED TRIAL”. Asian Journal of Pharmaceutical and Clinical Research, vol. 9, no. 3, May 2016, pp. 253-6, https://www.journals.innovareacademics.in/index.php/ajpcr/article/view/11161.