Toomey, T. C., Ghia, J. N., Mao, W., & Gregg, J. M. (1977). Acupuncture and chronic pain mechanisms: the moderating effects of affect, personality, and stress on response to treatment. Pain, 3(2), 137–145. http://www.elsevier.com/inca/publications/store/5/0/6/0/8/3/