RT Journal Article SR Electronic T1 Corticosteroid responsiveness and clinical characteristics in childhood difficult asthma JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society DO 10.1183/09031936.00186508 A1 C.J. Bossley A1 S. Saglani A1 C. Kavanagh A1 D.N.R. Payne A1 N. Wilson A1 L. Tsartsali A1 M. Rosenthal A1 I.M. Balfour-Lynn A1 A.G. Nicholson A1 A. Bush YR 2009 UL http://erj.ersjournals.com/content/early/2009/06/18/09031936.00186508.abstract AB