RT Journal Article SR Electronic T1 CTLA4 gene polymorphisms are associated with chronic bronchitis JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society DO 10.1183/09031936.00141808 A1 G. Zhu A1 A. Agusti A1 A. Gulsvik A1 P. Bakke A1 ICGN investigators A1 H. Coxson A1 D.A. Lomas A1 E.K. Silverman A1 S.G. Pillai YR 2009 UL http://erj.ersjournals.com/content/early/2009/04/22/09031936.00141808.abstract AB