1. GINA (Global Initiative for Asthma). http://www.ginasthma.com
2. British guideline on the management of asthma;BTS/SIGN (British Thoracic Society/Scottish Intercollegiate Guidelines Network).;Thorax,2003
3. Ease of handling and clinical efficacy of a new multi-dose dry powder inhaler for the delivery of salmeterol in adult asthmatics;Clay;Eur Respir J,1994
4. Turbutest in the training of asthmatic Turbuhaler users;Ferreira;Allergy,1999
5. Inhalation profiles in asthmatics and COPD patients: reproducibility and effect of instruction;Broeders;J Aerosol Med,2003