@incollection{Wieringa89,
  author	= {Wieringa, R.},
  editor	= {Falkenberg, E. D. and Lindgreen, P.},
  year		= {1989},
  title		= {Three roles of conceptual models in information system design and use},
  booktitle	= {Information system concept: an in-depth analysis},
  pages		= {31--52},
  publisher	= {North-Holland}
}