@book{Senne2011,
  author    = {Senne, Petra},
  title     = {Arbeitsrecht},
  publisher = {Vahlen},
  address   = {M{\"u}nchen},
  isbn      = {978-3-8006-3901-4},
  pages     = {311},
  year      = {2011},
  language  = {de}
}
@book{Senne2009,
  author    = {Senne, Petra},
  title     = {Arbeitsrecht},
  publisher = {Luchterhand},
  address   = {K{\"o}ln},
  isbn      = {978-3-472-07661-2},
  pages     = {XV, 274},
  year      = {2009},
  language  = {de}
}