PT - JOURNAL ARTICLE AU - Karemaker, J. M. TI - Heart rate variability: why do spectral analysis? AID - 10.1136/hrt.77.2.99 DP - 1997 Feb 01 TA - Heart PG - 99--101 VI - 77 IP - 2 4099 - http://heart.bmj.com/content/77/2/99.short 4100 - http://heart.bmj.com/content/77/2/99.full SO - Heart1997 Feb 01; 77