1. American Lung Association. COPD fact sheet. 2011. Available from:
http://www.lung.org/lung-disease/copd/resources/facts-figures/COPD-Fact-Sheet.html
. Last accessed June 6, 2013.
2. What is COPD? National Heart Lung and Blood Institute; U.S.Department of Health & Human Services, 2013. Available from:
http://www.nhlbi.nih.gov/health/health-topics/topics/copd
. Last accessed June 20, 2013.
3. Mannino DM, Homa DM, Akinbami LJ, Ford ES, Redd SC. Chronic obstructive pulmonary disease surveillance–United States, 1971–2000. Respir Care. 2002;47(10):1184–99.
4. Mannino DM. COPD: epidemiology, prevalence, morbidity and mortality, and disease heterogeneity. Chest. 2002;121(5 Suppl):121S–6.
5. Global Initiative for Chronic Obstructive Lung Disease (GOLD). Global Strategy for the Diagnosis, Management and Prevention of COPD, 2014. Available from:
http://www.goldcopd.org
. Last accessed December 17, 2014.