8Katsura H, Yamada K, Wakabayashi R, et al. The impact of dyspnoea and leg fatigue during exercise on health-related quality of life in patients with COPD[J]. Respirology, 2005, 10 (4):485-490.
9Corrado A, Renda T, Bertini S. Long-term oxygen therapy in COPD: evidences and open questions of current indications [J]. Monaldi Arch Chest Dis, 2010, 73(1):34-43.
10Soley MD, Shock NW. The etiology of effort syndrome[J]. Am J Med Sci, 1938,196:840.