Negro Calduch E, Diaz A, Diez M
HIV/AIDS Epidemiology Unit, Secretariat of the National Plan on AIDS, Directorate of Public Health and Border Health and National Epidemiology Centre, Instituto de Salud Carlos III, Madrid, Spain.
Euro Surveill. 2008 Dec 11;13(50):19061. doi: 10.2807/ese.13.50.19061-en.