PT - JOURNAL ARTICLE AU - M J DAVIES TI - Essential collection AID - 10.1136/hrt.80.2.107 DP - 1998 Aug 01 TA - Heart PG - 107--107 VI - 80 IP - 2 4099 - http://heart.bmj.com/content/80/2/107.short 4100 - http://heart.bmj.com/content/80/2/107.full SO - Heart1998 Aug 01; 80