@incollection{Stevens-Collins80,
  author	= {Stevens, A. L. and Collins, A.},
  editor	= {Snow, P. A. Federico R. E. and Montague, W. E.},
  year		= {1980},
  title		= {Multiple Conceptual Models of a Complex System},
  booktitle	= {Aptitude, Learning, and Instruction},
  pages		= {177--197},
  publisher	= {Erlbaum},
  address	= {Hillsdale, NJ}
}