RT Journal Article SR Electronic T1 Mucus hypersecretion in COPD: should we only rely on symptoms? JF European Respiratory Review JO EUROPEAN RESPIRATORY REVIEW FD European Respiratory Society SP 94 OP 96 DO 10.1183/09059180.00004410 VO 19 IS 116 A1 P-R. Burgel A1 C. Martin YR 2010 UL http://err.ersjournals.com/content/19/116/94.abstract AB