Submitted on: 18 September 2009.
Revised on: 15 January 2010.
Accepted on: 20 February 2010.
___________________International Journal of Chronic Obstructive Pulmonary Disease
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Submitted on: 15 September 2017.
Revised on: 03 November 2017.
Accepted on: 23 December 2017.
___________________International Journal of Chronic Obstructive Pulmonary Disease
Submitted on: 22 October 2014.
Revised on: 26 November 2014.
Accepted on: 13 January 2015.
___________________International Journal of Chronic Obstructive Pulmonary Disease
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