1. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders Fourth Edition (DSM-IV). Washington, DC: American Psychiatric As- sociation, 1994: 532–538.
2. Andrews ML. Manual of voice treatment: pediatrics through geriatrics. San Diego: Singular Publishing Group, Inc, 1995: 394–400.
3. Bornstein K. Gender outlaw. New York: Routledge, 1994: 118–21.
4. Evaluation of vocal pitch in male transsexuals
5. Case J. Clinical management of voice disorders. Austin, TX: Pro-ed, 1996: 256–7.