Bujedo, MD, Borja Mugabure, Silvia González Santos, MD, and Amaia Uría Azpiazu, MD. 2012. “A Review of Epidural and Intrathecal Opioids Used in the Management of Postoperative Pain”. Journal of Opioid Management 8 (3):177-92. https://doi.org/10.5055/jom.2012.0114.