Evaluation of health-related quality of life in low-income patients with COPD receiving long-term oxygen therapy - Ferreira, Cláudia Adriana Sant'Anna; Stelmach, Rafael; Feltrin, Maria Ignez Zanetti; Jacob Filho, Wilson; Chiba, Toshio; Cukier, Alberto (Chest - The Cardiopulmonary and Critical Care Journal, 2003)