Portenoy, MD, R. K., D. Bruns, PsyD, B. Shoemaker, BSN, and S. A. Shoemaker, MD. “Breakthrough Pain in Community-Dwelling Patients With Cancer Pain and Noncancer Pain, Part 1: Prevalence and Characteristics”. Journal of Opioid Management, vol. 6, no. 2, Jan. 2018, pp. 97-108, doi:10.5055/jom.2010.0009.