@incollection{HeidenG{\"o}bel2000,
  author    = {Heiden, W. and G{\"o}bel, M.},
  title     = {Virtuelle Umgebungen},
  booktitle = {Szczerbicka, Uthmann (Eds.): Modellierung, Simulation und K{\"u}nstliche Intelligenz. Statusband},
  isbn      = {1-56555-128-1},
  institution = {Fachbereich Informatik},
  pages     = {139 -- 173},
  year      = {2000},
  language  = {en}
}