1. COPD in Japan: the Nippon COPD epidemiology study;Fukuchi;Respirology,2004
2. Prevalence of chronic obstructive pulmonary disease in Japanese people on medical check-up;Takemura;Tohoku J Exp Med,2005
3. Global Initiative for Chronic Obstructive Lung Disease (GOLD). Global Strategy for the Diagnosis, Management, and Prevention of Chronic Obstructive Pulmonary Disease. Updated 2014. 〈http://www.goldcopd.org/guidelines-global-strategy-for-diagnosis-management.html〉; 2014 [Last accessed 25.08.14].
4. Committee for the third edition of the COPD guidelines of the Japanese Respiratory Society. Guidelines for the diagnosis and treatment of COPD (Chronic Obstructive Pulmonary Disease). 3rd ed. Tokyo: Medical Review Co. Ltd 2009. Available at: 〈www.jrs.or.jp/uploads/uploads/files/photos/765.pdf〉; 2014 [Last accessed 25.08.14].
5. Comparison of tiotropium once daily, formoterol twice daily and both combined once daily in patients with COPD;van Noord;Eur Respir J,2005