@inproceedings{popowich-1989-tree,
    title = "Tree Unification Grammar",
    author = "Popowich, Fred",
    booktitle = "27th Annual Meeting of the Association for Computational Linguistics",
    month = jun,
    year = "1989",
    address = "Vancouver, British Columbia, Canada",
    publisher = "Association for Computational Linguistics",
    url = "https://preview.aclanthology.org/fix-sig-urls/P89-1028/",
    doi = "10.3115/981623.981651",
    pages = "228--236"
}