Freye, MD, PhD, E., Hartung, MD, E. and Levy, PhD, J. V. (2005) “No potentiation of fentanyl by use of transdermal buprenorphine in patients undergoing fast-track anesthesia for open-heart surgery”, Journal of Opioid Management, 1(3), pp. 162–167. doi: 10.5055/jom.2005.0036.