@InProceedings{evans:1997:ACL,
  author    = {Edmund Grimley Evans},
  title     = {Approximating Context-Free Grammars with a Finite-State Calculus},
  booktitle = {Proceedings of the 35th Annual Meeting of the Association for Computational Linguistics},
  month     = {July},
  year      = {1997},
  address   = {Madrid, Spain},
  publisher = {Association for Computational Linguistics},
  pages     = {452--459},
  url       = {http://www.aclweb.org/anthology/P97-1058},
  doi       = {10.3115/976909.979675}
}