Hurst J R, Wedzicha J A
Academic Unit of Respiratory Medicine, Royal Free & University College Medical School, Rowland Hill Street, London NW3 2PF, UK.
Thorax. 2007 Mar;62(3):198-9. doi: 10.1136/thx.2007.077883.
Definition of what is (and what is not) a COPD exacerbation