@inproceedings{wang-etal-2021-cluster,
    title = "Cluster-Former: Clustering-based Sparse Transformer for Question Answering",
    author = "Wang, Shuohang  and
      Zhou, Luowei  and
      Gan, Zhe  and
      Chen, Yen-Chun  and
      Fang, Yuwei  and
      Sun, Siqi  and
      Cheng, Yu  and
      Liu, Jingjing",
    editor = "Zong, Chengqing  and
      Xia, Fei  and
      Li, Wenjie  and
      Navigli, Roberto",
    booktitle = "Findings of the Association for Computational Linguistics: ACL-IJCNLP 2021",
    month = aug,
    year = "2021",
    address = "Online",
    publisher = "Association for Computational Linguistics",
    url = "https://preview.aclanthology.org/fix-sig-urls/2021.findings-acl.346/",
    doi = "10.18653/v1/2021.findings-acl.346",
    pages = "3958--3968"
}