Fetuin-A is Associated with Disease Severity and Exacerbation Frequency in Patients with COPD. - Minas, Markos; Mystridou, Parthena; Georgoulias, Panagiotis; Pournaras, Spyros; Kostikas, Konstantinos; Gourgoulianis, Konstantinos I. (COPD: Journal of Chronic Obstructive Pulmonary Disease, 2013)