International approaches to the prescription of long-term oxygen therapy
P.J. Wijkstra, G.H. Guyatt, N. Ambrosino, B.R. Celli, R. Güell, J.F. Muir, C. Préfaut, E.S. Mendes, I. Ferreira, P. Austin, B. Weaver, R.S. Goldstein
European Respiratory Journal Dec 2001, 18 (6) 909-913; DOI: 10.1183/09031936.01.00202301