1. Behavioural surveillance: the value of national coordination;CA McGarrigle,2002
2. World Health Organization and Joint United Nations Programme on HIV/AIDS. Second generation surveillance for HIV: the next decade. 2000. Available from: http://www.who.int/hiv/pub/surveillance/en/cds_edc_2000_5.pdf [last accessed: 6 May 2015]
3. World Health Organization and Joint United Nations Programme on HIV/AIDS. Guidelines for measuring national HIV prevalence in population-based surveys. 2005. Available from: http://www.who.int/hiv/pub/surveillance/guidelinesmeasuringpopulation.pdf?ua=1 [last accessed: 6 May 2015]
4. Surveillance of sexually transmitted infections in primary care;I Simms,2003
5. Nonprobability web surveys to measure sexual behaviors and attitudes in the general population: A comparison with a probability sample interview survey;B Erens,2014