@inproceedings{krotov-etal-1998-compacting-penn,
    title = "Compacting the {P}enn {T}reebank Grammar",
    author = "Krotov, Alexander  and
      Hepple, Mark  and
      Gaizauskas, Robert  and
      Wilks, Yorick",
    booktitle = "36th Annual Meeting of the Association for Computational Linguistics and 17th International Conference on Computational Linguistics, Volume 1",
    month = aug,
    year = "1998",
    address = "Montreal, Quebec, Canada",
    publisher = "Association for Computational Linguistics",
    url = "https://preview.aclanthology.org/fix-sig-urls/P98-1115/",
    doi = "10.3115/980845.980962",
    pages = "699--703"
}