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\bibitem{DeBacker_etal2011} {\textquotedblleft}\textit{The effects of long-term noninvasive ventilation in hypercapnic COPD patients : a randomized controlled pilot study}{\textquotedblright}. De Backer L, Vos W, Dieriks B, Daems D, Verhulst S, Vinchurkar S, Ides K, de Backer J, Germonpr{\'e} P, de Backer W, International journal of chronic obstructive pulmonary disease \textbf{6}, 615 (2011).   http://doi.org/10.2147/COPD.S22823

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