RT Journal Article SR Electronic T1 Idiopathic pulmonary fibrosis: tracking the true occurrence is challenging JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP 604 OP 606 DO 10.1183/13993003.00958-2015 VO 46 IS 3 A1 Jonathan M. Samet A1 David Coultas A1 Ganesh Raghu YR 2015 UL http://erj.ersjournals.com/content/46/3/604.abstract AB