Vardenafil in pulmonary arterial hypertension: a randomized, double-blind, placebo-controlled study - Jing, Z-C; Yu, Z-X; Shen, J-Y (Am J Respir Crit Care Med, 2011)
, et al; Efficacy and Safety of Vardenafil in the Treatment of Pulmonary Arterial Hypertension (EVALUATION) Study Group.