Unexplained Syncope Evaluated by Electrophysiologic Studies and Head-up Tilt Testing
Ann Int Med 114:1013-1019, Sra,J.S.,et al, 1991
Intracardiac Electrophysiologic Techniques in Recurrent Syncope of Unknown Cause
Ann Int Med 95:542-548, DiMarco,J.P.,et al, 1981