1. Kaplan HI, Sadock BJ. Synopsis of psychiatry,8th edition. New York: Lippincott Williams and Willikins; 1998. Chapter 3, pp. 864–872.
2. Andreason NC, Black DW. Introductory Textbook of Psychiatry, 8th edition. Washington DC: American Psychiatry Press; 1995. Chapter 20, pp. 511–524.