RT Journal Article SR Electronic T1 β2 adrenergic receptor polymorphisms and COPD exacerbations: a complicated story JF Thorax JO Thorax FD BMJ Publishing Group Ltd and British Thoracic Society SP 927 OP 928 DO 10.1136/thoraxjnl-2019-213697 VO 74 IS 10 A1 Wassim W Labaki A1 MeiLan K Han YR 2019 UL http://thorax.bmj.com/content/74/10/927.abstract AB