RT Journal Article SR Electronic T1 Adjusted-dose warfarin for atrial fibrillation reduced stroke risk better than low-dose warfarin plus aspirin JF Evidence Based Medicine JO Evid Based Med FD BMJ Publishing Group Ltd SP 19 OP 19 DO 10.1136/ebm.1997.2.19 VO 2 IS 1 YR 1997 UL http://ebm.bmj.com/content/2/1/19.abstract AB