RT Journal Article SR Electronic T1 Lack of clinically relevant differences between combination therapy and monotherapy in COPD JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP 1204 OP 1205 DO 10.1183/09031936.00156313 VO 43 IS 4 A1 Eric Bateman YR 2014 UL http://erj.ersjournals.com/content/43/4/1204.2.abstract AB