"GOLD or lower limit of normal definition? a comparison with expert-based diagnosis of chronic obstructive pulmonary disease in a prospective cohort-study" oleh Güder Gülmisal, Brenner Susanne, Angermann Christiane E, Ertl Georg, Held Matthias, Sachs Alfred P, Lammers Jan-Willem, Zanen Pieter, Hoes Arno W, Störk Stefan, Rutten Frans H