RT Journal Article SR Electronic T1 Estimating STI morbidity in primary care JF Sexually Transmitted Infections JO Sex Transm Infect FD BMJ Publishing Group Ltd SP 67 OP 67 DO 10.1136/sti.2005.017772 VO 82 IS 1 A1 J A Cassell YR 2006 UL http://sti.bmj.com/content/82/1/67.abstract AB