RT Journal Article SR Electronic T1 Assessing the safety of drugs through observational research JF Heart JO Heart FD BMJ Publishing Group Ltd and British Cardiovascular Society SP 129 OP 130 DO 10.1136/hrt.2007.114785 VO 94 IS 2 A1 Ross J Simpson, Jr YR 2008 UL http://heart.bmj.com/content/94/2/129.abstract AB