O’Mahony, MB BCh, BAO, S., J. L. Goulet, PhD, and R. Payne, MD. “Psychosocial Distress in Patients Treated for Cancer Pain: A Prospective Observational Study”. Journal of Opioid Management, vol. 6, no. 3, Jan. 2018, pp. 211-22, doi:10.5055/jom.2010.0019.