@incollection{Kobsa89-book,
  author	= {Kobsa, Alfred},
  editor	= {Kobsa, Alfred and Wahlster, Wolfgang},
  year		= {1989},
  title		= {A taxonomy of beliefs and goals for user models in dialog systems},
  pages		= {52--68},
  booktitle	= {User models in dialog systems},
  publisher	= {Springer},
  address	= {Berlin},
}