Zaman, Zaki Anwar, and Deepak Kumar. 2017. “Evaluation of Analgesic Effect of Tapentadol, a Central Novel Analgesic Versus Tramadol, a Widely Used Opioid Analgesic in Treatment of Low Back Pain: A Randomized Controlled Trial”. International Journal of Basic & Clinical Pharmacology 2 (4):392-96. https://www.ijbcp.com/index.php/ijbcp/article/view/1287.