RT Journal Article SR Electronic T1 The socio-economic status is related to the incidence of asthma and respiratory symptoms in adults JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society DO 10.1183/09031936.06.00108105 A1 U. Hedlund A1 K. Eriksson A1 E. Rönmark YR 2006 UL http://erj.ersjournals.com/content/early/2006/03/15/09031936.06.00108105.abstract AB