P. N. Zannikos, PhD, J. W. Smit, PhD, H.-J. Stahlberg, MD, B. Wenge, PhD, V. M. Hillewaert, MSc, and M. S. Etropolski, MD, “Pharmacokinetic evaluation of tapentadol extended-release tablets in healthy subjects”, J of Opioid Management, vol. 9, no. 4, pp. 291–300, Jul. 2013.