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Jatakanon A, Lim S, Kharitonov SA, Chung KF, Barnes PJ.Jatakanon A, et al. Among authors: chung kf.Thorax. 1998 Feb;53(2):91-5. doi: 10.1136/thx.53.2.91.Thorax. 1998.PMID: 9624291Free PMC article.
Hayes JP, Chung KF, Barnes PJ.Hayes JP, et al. Among authors: chung kf.Eur Respir J. 1992 Nov;5(10):1193-6.Eur Respir J. 1992.PMID: 1336735Clinical Trial.