1. Anonimous (1991): HIV counselling in the 1990s ?Lancet 337: 950.
2. Cavalier A., Ancelle-Park R., Birkui P., Helal H., Poinsard H. and Pretet S. (1990): Trends of the epidemic in the population of two anonymous and free HIV testing centres, Paris-France ? VI International Conference on AIDS, San Francisco 1990 (abstract F.C. 620).
3. Centers for Disease Control (1987): Public Health Service Guidelines for counseling, and antibody testing to prevent HIV infection and AIDS - MMWR 36: 509?514.
4. Centers for Disease Control (1990): Publicly funded HIV counseling and testing-United States, 1985?1989- MMWR 39: 137?152.
5. Centro Operativo AIDS (1991): Aggiornamento dei casi di AIDS conclamato notificati in Italia al 30 settembre 1991 - Istituto Superiore di Sanit�, Roma.