RT Journal Article SR Electronic T1 The role of atypical respiratory pathogens in exacerbations of chronic obstructive pulmonary disease JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society DO 10.1183/09031936.00012707 A1 B.M.W. Diederen A1 P.D.L.P.M. van der Valk A1 J.A.W.J. Kluytmans A1 M.F. Peeters A1 R. Hendrix YR 2007 UL http://erj.ersjournals.com/content/early/2007/04/25/09031936.00012707.abstract AB