Vorsanger, PhD, MD, G. J., Xiang, PhD, J., Gana, MD, PhD, T. J., Pascual, MD, MPH, M. L. G. and Fleming, MS, R. R. B. (2018) “Extended-release tramadol (tramadol ER) in the treatment of chronic low back pain”, Journal of Opioid Management, 4(2), pp. 87–97. doi: 10.5055/jom.2008.0013.