RT Journal Article SR Electronic T1 Warfarin was cost-effective for stroke prophylaxis in nonvalvular atrial fibrillation with additional risk factors JF Evidence Based Medicine JO Evid Based Med FD BMJ Publishing Group Ltd SP 128 OP 128 DO 10.1136/ebm.1996.1.128 VO 1 IS 4 YR 1996 UL http://ebm.bmj.com/content/1/4/128.abstract AB