RT Journal Article SR Electronic T1 Principles, progress and harm in the Guatemala Syphilis Study JF Sexually Transmitted Infections JO Sex Transm Infect FD BMJ Publishing Group Ltd SP 303 OP 303 DO 10.1136/sextrans-2013-051113 VO 89 IS 4 A1 David Gurnham YR 2013 UL http://sti.bmj.com/content/89/4/303.abstract AB