@inproceedings{zhang-etal-2021-open,
    title = "Open Hierarchical Relation Extraction",
    author = "Zhang, Kai  and
      Yao, Yuan  and
      Xie, Ruobing  and
      Han, Xu  and
      Liu, Zhiyuan  and
      Lin, Fen  and
      Lin, Leyu  and
      Sun, Maosong",
    editor = "Toutanova, Kristina  and
      Rumshisky, Anna  and
      Zettlemoyer, Luke  and
      Hakkani-Tur, Dilek  and
      Beltagy, Iz  and
      Bethard, Steven  and
      Cotterell, Ryan  and
      Chakraborty, Tanmoy  and
      Zhou, Yichao",
    booktitle = "Proceedings of the 2021 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language Technologies",
    month = jun,
    year = "2021",
    address = "Online",
    publisher = "Association for Computational Linguistics",
    url = "https://preview.aclanthology.org/fix-sig-urls/2021.naacl-main.452/",
    doi = "10.18653/v1/2021.naacl-main.452",
    pages = "5682--5693"
}