Improving Named Entity Recognition by External Context Retrieving and Cooperative Learning Xinyu Wang author Yong Jiang author Nguyen Bach author Tao Wang author Zhongqiang Huang author Fei Huang author Kewei Tu author 2021-08 text 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) Chengqing Zong editor Fei Xia editor Wenjie Li editor Roberto Navigli editor Association for Computational Linguistics Online conference publication wang-etal-2021-improving 10.18653/v1/2021.acl-long.142 https://aclanthology.org/2021.acl-long.142/ 2021-08 1800 1812