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American Cancer Society.
American Lung Association.
Brunton, S. American Journal of Managed Care, October 2004.
Centers for Disease Control and Prevention.
ERS Task Force. European Respiratory Journal, September 2004.
Martinez, F. Comprehensive Therapy, Spring 2004.
National Institutes of Health.
Smucny, J. Cochrane Database System Reviews, October 2004.
Steinman, M. American Journal of Geriatric Society, June 2004.
University of California San Francisco Medical Center.
Reviewed by Jennifer Robinson, MD on January 11, 2018
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