@article{zhu2019did,
  title={Who did They Respond to? Conversation Structure Modeling using Masked Hierarchical Transformer},
  author={Zhu, Henghui and Nan, Feng and Wang, Zhiguo and Nallapati, Ramesh and Xiang, Bing},
  journal={arXiv preprint arXiv:1911.10666},
  year={2019}
}