RT Journal Article SR Electronic T1 Postal research: too many problems? JF Sexually Transmitted Infections JO Sex Transm Infect FD BMJ Publishing Group Ltd SP 332 OP 334 DO 10.1136/sti.76.5.332 VO 76 IS 5 A1 S M Bates A1 K E Rogstad YR 2000 UL http://sti.bmj.com/content/76/5/332.abstract AB