M. Das, MBBS, MD, R. Jain, MSc, PhD, CChem FRSC (UK), A. Dhawan, MBBS, MD, and A. Kaur, MBBS, MD, “Assessment of abuse liability of Tramadol among experienced drug users: Double-blind crossover randomized controlled trial”, J of Opioid Management, vol. 12, no. 6, pp. 421–430, Nov. 2016.