@incollection{HeidenGoebel2000,
  author    = {W. Heiden and M. G{\"o}bel},
  title     = {Virtuelle Umgebungen},
  series = {Szczerbicka, Uthmann (Eds.): Modellierung, Simulation und K{\"u}nstliche Intelligenz. Statusband},
  publisher = {SCS-Europe},
  address   = {Ghent},
  isbn      = {1-56555-128-1},
  pages     = {139 -- 173},
  year      = {2000},
  language  = {en}
}