A randomized, double-blind, active-controlled, parallel-group comparison of valsartan and amlodipine in the treatment of isolated systolic hypertension in elderly patients: the Val-Syst study. - Malacco E; Vari N; Capuano V; Spagnuolo V; Borgnino C; Palatini P; Val-Syst Investigators (Clinical Therapeutics, 2003)