TY  - RPRT
TI  - COPD exacerbations: definitions and classifications.
AU  - S Burge
AU  - J A Wedzicha
PY  - 2003
DO  - 10.1183/09031936.03.00078002
UR  - https://pubmed.ncbi.nlm.nih.gov/12795331/
ID  - 12795331
ER  -