Effect of left ventricular stimulation site on the systolic function of heart failure patients during ventricular resynchronization therapy. - Butter, C.; Auricchio, A.; Stellbrink, C.; Fleck, E.; Ding, J.; Michel, U.; Kramer, A.; Maarse, A.; Salo, R.; Spinelli, J. (European Journal of Heart Failure, 2000)