Clinical correlates and prognostic significance of six-minute walk test in patients with primary pulmonary hypertension. Comparison with cardiopulmonary exercise testing. - Miyamoto,S.; Nagaya,N.; Satoh,T.; Kyotani,S.; Sakamaki,F.; Fujita,M.; Nakanishi,N.; Miyatake,K. (Am J Respir Crit Care Med, 2000)