@misc{9323,
  author = {H. Mullerova and A. Shukla and A. Hawkins and J. Quint},
  title = {Risk factors for acute exacerbations of COPD in a primary care population: a retrospective observational cohort study},
  year = {2014},
  journal = {BMJ Open},
  volume = {4},
  number = {12},
  pages = {e006171},
  issn = {2044-6055},
  doi = {10.1136/bmjopen-2014-006171},
}