[Rare conditions are rare].

@article{Brekke2009RareCA,
  title={[Rare conditions are rare].},
  author={Mette Brekke},
  journal={Tidsskrift for den Norske laegeforening : tidsskrift for praktisk medicin, ny raekke},
  year={2009},
  volume={129 24},
  pages={2615-6}
}