@inproceedings{knowwhatyoudontknowunanswerable,
  title = {Know What You Don't Know: Unanswerable Questions for SQuAD},
  author = {Pranav Rajpurkar and Robin Jia and Percy Liang},
  year = {2018},
  booktitle = {ACL 2018 7},
  eprint = {1806.03822},
  archivePrefix = {arXiv},
  url = {http://arxiv.org/abs/1806.03822v1},
}