@article{Kaufmann:2009sm,
  author = "Kaufmann, Sarah  and  Wagner, Stefan",
  title = "{X ray spectral variability of TeV Blazars}",
  doi = "10.22323/1.063.0044",
  journal = "PoS",
  year = 2009,
  volume = "BLAZARS2008",
  pages = "044"
}