@inproceedings{unitedqaahybridapproachforopendomain,
  title = {UnitedQA: A Hybrid Approach for Open Domain Question Answering},
  author = {Hao Cheng and Yelong Shen and Xiaodong Liu and Pengcheng He and Weizhu Chen and Jianfeng Gao},
  year = {2021},
  booktitle = {ACL 2021 5},
  eprint = {2101.00178},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2101.00178v2},
}