TY - JOUR AU - Dreher, M; Doncheva, E; Schwoerer, A TI - Preserving Oxygenation during Walking in Severe Chronic Obstructive Pulmonary Disease: Noninvasive Ventilation versus Oxygen Therapy JO - Respiration VL - 78 PY - 2009 DO - 10.1159/000187717 L3 - PubMed-ID: 19092234 SP - 154 EP - 160 N1 - et al. ER -