1. Rothman K (1986) Modern epidemiology. Little Brown, Boston
2. Cohen K et al Psychological characteristics and sexuality of natal males with gender dysphoria
3. WHO Library (1975) International statistical classification of diseases and related health problems. 9th revision, Geneva
4. American Psychiatric Association (1980) Diagnostic and statistical manual of mental disorders (third edition, DSM-III). American Psychiatric Association, Washington, DC
5. WHO Library (1980) International statistical classification of diseases and related health problems. 10th revision, Geneva