@InProceedings{okanohara-tsujii:2009:NAACLHLT09-Short,
  author    = {Okanohara, Daisuke  and  Tsujii, Jun'ichi},
  title     = {Learning Combination Features with L1 Regularization},
  booktitle = {Proceedings of Human Language Technologies: The 2009 Annual Conference of the North American Chapter of the Association for Computational Linguistics, Companion Volume: Short Papers},
  month     = {June},
  year      = {2009},
  address   = {Boulder, Colorado},
  publisher = {Association for Computational Linguistics},
  pages     = {97--100},
  url       = {http://www.aclweb.org/anthology/N/N09/N09-2025}
}