Authors V. Mark Durand, M.V. & Barlow, D.H. (2009) Essentials of Abnormal Psychologyp.436. Cengage Learning. ISBN 0-495-59982-4. Retrieved November 2011
Maddux, J.E. & Winstead, B.A. (2005) Psychopathology: foundations for a contemporary understandingp.77. Routledge. ISBN 0-8058-4077-X Retrieved November 2011