RT Journal Article SR Electronic T1 Apex cardiogram and systolic time intervals in acute myocardial infarction. JF British Heart Journal JO Heart FD BMJ Publishing Group Ltd and British Cardiovascular Society SP 578 OP 584 DO 10.1136/hrt.33.4.578 VO 33 IS 4 A1 S R Jain A1 J Lindahl YR 1971 UL http://heart.bmj.com/content/33/4/578.abstract AB