References
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Global Initiative for Chronic Obstructive Lung Disease (GOLD). “Global Strategy for the Diagnosis, Management and Prevention of COPD, 2010.” (accessed November 9, 2015) Gold Report
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2: World Health Organization. “Chronic respiratory diseases: Burden of COPD” (accessed November 9, 2015) http://www.who.int/gho/publications/world_health_statistics/en/