@incollection{FreksaBarkowsky99-duality,
  author	= {Freksa, C. and Barkowsky, T.},
  editor	= {Rickheit, G. and Habel, C.},
  title		= {On the duality and on the integration of propositional and spatial representations},
  booktitle	= {Mental Models in Discourse Processing and Reasoning},
  pages		= {195--212},
  publisher	= {Elsevier},
  year		= {1999},
  address	= {Amsterdam, Lausanne, New York}
}