title: Safe, safer, safest: the hierarchy of sexual risk behaviors for HIV.
authors.forename: Amie M
authors.initials: AM
authors.lastname: Ashcraft
authors.forename: Willi
authors.initials: W
authors.lastname: McFarland
mesh_terms: D015658:HIV Infections / Q000523:psychology* / Q000635:transmission*; D006801:Humans; D012309:Risk-Taking; D021841:Safe Sex; D012725:Sexual Behavior; D012747:Sexual Partners; D019562:Viral Load