Original article Longitudinal validity of spirometers - a challenge in longitudinal studies B Kuna-Dibbert, D Keidel, KM Schweinzer, P Leuenberger, U Ackermann-Liebrich DOI: https://doi.org/10.4414/smw.2005.11050 Publication Date: 27.08.2005 Swiss Med Wkly. 2005;135(33-34):503-508 This text is only available as PDF .