@article{Pereira-Warren80,
  author	= {Pereira, F. C. N. and Warren, D. H. D.},
  year		= {1980},
  title		= {Definite Clause Grammars for Language Analysis - A Survey of the Formalism and a Comparison with Augmented Transition Network},
  journal	= {Artificial Intelligence},
  pages		= {231--278}
}