1. Diagnostic and statistical manual of mental disorders;American Psychiatric Association (APA),1994
2. International Classification of Diseases;World Health Organization,1994
3. The standards of care for gender identity disorders—Sixth version;Meyer;IJT,2001
4. Becker S,Bosinski HAG,Clement U,Eicher WM,Goerlich TM,Hartmann U,Kockott G,Langer D,Preuss W,Schmidt G,Springer G,Springer A,Wille R.German standards for the treatment and diagnostic assessment of transsexuals. Available at http://www.symposion.com/ijt/ijtc0603.htm. (accessed July 30, 2007).
5. The prevalence of transsexualism in Singapore;Tsoi;Acta Psychiatr Scand,1988