PT - JOURNAL ARTICLE AU - Shawn D. Aaron TI - Measuring and quantifying acute exacerbations of COPD: pitfalls and practicalities AID - 10.1183/09031936.00158613 DP - 2014 Mar 01 TA - European Respiratory Journal PG - 662--664 VI - 43 IP - 3 4099 - http://erj.ersjournals.com/content/43/3/662.short 4100 - http://erj.ersjournals.com/content/43/3/662.full SO - Eur Respir J2014 Mar 01; 43