1. HIV/AIDS. Fact Sheet World Health Organisation, Geneva, Switzerland;WHO,2018
2. Global HIV & AIDS statistics– 2018 fact sheet;UNAIDS;Joint United Nations Programme on HIV/AIDS Geneva, Switzerland,2018
3. CDC. About HIV/AIDS. HIV Basics. Centers for Disease Control and Prevention. 2019. https://www.cdc.gov/hiv/basics/whatishiv.html.