@inproceedings{ijcai2009p172,
  title     = {Selecting Informative Universum Sample for Semi-Supervised Learning},
  author    = {Chen, Shuo and Zhang, Changshui},
  booktitle = {Proceedings of the Twenty-First International Joint Conference on
               Artificial Intelligence, {IJCAI-09}},
  publisher = {International Joint Conferences on Artificial Intelligence},
  editor    = {Hiroaki Kitano},
  pages     = {1016--1020},
  year      = {2009},
  url       = {https://ijcai.org/proceedings/2009/172},
}