RT Journal Article SR Electronic T1 Clustering in asthma: why, how and for how long? JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP 1247 OP 1248 DO 10.1183/09031936.00003313 VO 41 IS 6 A1 Arnaud Bourdin A1 Pascal Chanez YR 2013 UL http://erj.ersjournals.com/content/41/6/1247.abstract AB