1. Epidemiology Unit, Aviano Cancer Center, Aviano (Pordenone), Denver, Colorado, U.S.A.
2. European Organization for Cooperation for Cancer Prevention Studies - Hormones, Sexual Factors & Cancer Group, Denver, Colorado, U.S.A.
3. Dept. of Preventive Medicine and Biometrics, Unversity of Colorado Health Sciences Center, Denver, Colorado, U.S.A.
4. « Mario Negri » Institute for Pharmacological Research, Milan
5. Institute of Social and Preventive Medicine, University of Lausanne, Lausanne, Switzerland