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Merkus PJ, van Pelt W, van Houwelingen JC, van Essen-Zandvliet LE, Duiverman EJ, Kerrebijn KF, Quanjer PH.Merkus PJ, et al.Eur Respir J. 2004 Jun;23(6):861-8. doi: 10.1183/09031936.04.00031504.Eur Respir J. 2004.PMID: 15218999Free article.Clinical Trial.