Sumida, MD, S., Lesley, BS, M.R., Hanna, MD, M.N., Murphy, MD, J.D., Kumar, MD, K. and Wu, MD, C.L. 2018. Meta-analysis of the effect of extended-release epidural morphine versus intravenous patient-controlled analgesia on respiratory depression. Journal of Opioid Management. 5, 5 (Jan. 2018), 301–305. DOI:https://doi.org/10.5055/jom.2009.0030.