The effect of long-term oxygen therapy on 6-minute walking distance, clinical parameters and hemodynamics in patients with pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension. A prospective, randomized, controlled trial (SOPHA Study) - Xanthouli, P; Echampati, I; Harutyunova, S; Benjamin, N; Eichstaedt, C; Egenlauf, B; Salkič, A; Grünig, E (Pneumologie, 2023)