@inproceedings{azuma-matsumoto-2011-multilayer,
    title = "Multilayer Sequence Labeling",
    author = "Azuma, Ai  and
      Matsumoto, Yuji",
    editor = "Barzilay, Regina  and
      Johnson, Mark",
    booktitle = "Proceedings of the 2011 Conference on Empirical Methods in Natural Language Processing",
    month = jul,
    year = "2011",
    address = "Edinburgh, Scotland, UK.",
    publisher = "Association for Computational Linguistics",
    url = "https://preview.aclanthology.org/fix-sig-urls/D11-1058/",
    pages = "628--637"
}