RT Journal Article SR Electronic T1 The development of cardiac rhythm JF Heart JO Heart FD BMJ Publishing Group Ltd and British Cardiovascular Society SP 874 OP 875 DO 10.1136/hrt.2004.047415 VO 91 IS 7 A1 J Boullin A1 J M Morgan YR 2005 UL http://heart.bmj.com/content/91/7/874.abstract AB