@inproceedings{ijcai2007p274,
  title     = {Subtree Mining for Question Classification Problem},
  author    = {Le Nguyen, Minh and Tri, Nguyen Thanh and Shimazu, Akira},
  booktitle = {Proceedings of the Twentieth International Joint Conference on
               Artificial Intelligence, {IJCAI-07}},
  publisher = {International Joint Conferences on Artificial Intelligence},
  editor    = {Ramon López de Mántaras},
  pages     = {1695--1699},
  year      = {2007},
  url       = {https://ijcai.org/proceedings/2007/274},
}