Bagby, R. M., Ryder, A. G., Ben Dat, D., Bacchiochi, J., & Parker, J. D. A. (2002). Validation of the dimensional factor structure of the personality psychopathology five in clinical and nonclinical samples. Journal of Personality Disorders, 16(4), 304–316. http://www.guilford.com/cartscript.cgi?page=periodicals/jnpd.htm\&cart\_id=547216.21319