Williams, D. E., Thompson, J. K., Haber, J. D., & Raczynski, J. M. (1986). MMPI and headache: a special focus on differential diagnosis, prediction of treatment outcome, and patient-treatment matching. Pain, 24(2), 143–158. http://www.elsevier.com/inca/publications/store/5/0/6/0/8/3/