Casaburi R, Porszasz J, Hecht A, Tiep B, Albert RK, Anthonisen NR, Bailey WC, Connett JE, Cooper JA, Criner GJ, Curtis J, Dransfield M, Lazarus SC, Make B, Martinez FJ, McEvoy C, Niewoehner DE, Reilly JJ, Scanlon P, Scharf SM, Sciurba FC, Woodruff P. Influence of lightweight ambulatory oxygen on oxygen use and activity patterns of COPD patients receiving long-term oxygen therapy. COPD. 2012 Feb; 9(1):3-11.