RT Journal Article SR Electronic T1 Recruitment in online research for COPD: leveraging social media and research registries JF ERJ Open Research JO erjor FD European Respiratory Society SP 00167-2018 DO 10.1183/23120541.00167-2018 VO 5 IS 2 A1 Samantha R. Paige A1 Janice L. Krieger YR 2019 UL http://openres.ersjournals.com/content/5/2/00167-2018.abstract AB