@article{Hebel2011,
  author    = {Hebel, Christoph},
  title     = {Anwendungen von makroskopischen Personenverkehrsnachfragemodellen},
  series = {Stadt Region Land. 2011 (2011), H. 88},
  journal   = {Stadt Region Land. 2011 (2011), H. 88},
  publisher = {ISB},
  address   = {Aachen},
  isbn      = {978-3-88354-162-4},
  pages     = {7 -- 14},
  year      = {2011},
  language  = {de}
}
@article{Hebel2009,
  author    = {Hebel, Christoph},
  title     = {Einsatz von makroskopischen Personalnachfragemodellen in der Planungspraxis},
  series = {Stadt Region Land (2009)},
  journal   = {Stadt Region Land (2009)},
  publisher = {ISB},
  address   = {Aachen},
  isbn      = {978-3-88354-157-0},
  pages     = {63 -- 66},
  year      = {2009},
  language  = {de}
}