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Simpson JL, Powell H, Boyle MJ, Scott RJ, Gibson PG.Simpson JL, et al. Among authors: scott rj.Am J Respir Crit Care Med. 2008 Jan 15;177(2):148-55. doi: 10.1164/rccm.200707-1134OC. Epub 2007 Oct 18.Am J Respir Crit Care Med. 2008.PMID: 17947611Clinical Trial.