@inproceedings{slack-1990-unbounded,
    title = "Unbounded Dependency: Tying strings to rings",
    author = "Slack, Jon M.",
    booktitle = "{COLING} 1990 Volume 3: Papers presented to the 13th International Conference on Computational Linguistics",
    year = "1990",
    url = "https://aclanthology.org/C90-3047/"
}