%0 Journal Article %A Y. Ling %A W. Saleem %A C. D. Shee %T Concomitant use of β-blockers and β2-agonists %D 2008 %R 10.1183/09031936.00153707 %J European Respiratory Journal %P 905-906 %V 31 %N 4 %U https://erj.ersjournals.com/content/erj/31/4/905.full.pdf