1) van der PALEN J. Evaluation of the effectivceness of four different inhalers in patients with chronic obstructive pulmonary disease. Thorax. (1995) vol.50, p.1183-1187.
2) SHIEH W. B. Preference for the Diskhaler rather than the metered dose inhaler in patients with airway obstruction. Chang. Gung. Med. J.. (1994) vol.17, p.20-27.
3) KESTEN S. Patient handling of a multidose dry powder inhalation device for albuterol. Chest. (1081) vol.105, p.1077.