Frequent exacerbations in chronic obstructive pulmonary disease.

@article{George2011FrequentEI,
  title={Frequent exacerbations in chronic obstructive pulmonary disease.},
  author={Christina George and Will Zermansky and John R. Hurst},
  journal={BMJ},
  year={2011},
  volume={342},
  pages={d1434}
}