@inproceedings{yang-etal-2021-xmoco,
    title = "x{M}o{C}o: Cross Momentum Contrastive Learning for Open-Domain Question Answering",
    author = "Yang, Nan  and
      Wei, Furu  and
      Jiao, Binxing  and
      Jiang, Daxing  and
      Yang, Linjun",
    editor = "Zong, Chengqing  and
      Xia, Fei  and
      Li, Wenjie  and
      Navigli, Roberto",
    booktitle = "Proceedings of the 59th Annual Meeting of the Association for Computational Linguistics and the 11th International Joint Conference on Natural Language Processing (Volume 1: Long Papers)",
    month = aug,
    year = "2021",
    address = "Online",
    publisher = "Association for Computational Linguistics",
    url = "https://aclanthology.org/2021.acl-long.477/",
    doi = "10.18653/v1/2021.acl-long.477",
    pages = "6120--6129"
}