@InProceedings{bird:2006:IP,
  author    = {Bird, Steven},
  title     = {{NLTK}: The {Natural} {Language} {Toolkit}},
  booktitle = {Proceedings of the COLING/ACL 2006 Interactive Presentation Sessions},
  month     = {July},
  year      = {2006},
  address   = {Sydney, Australia},
  publisher = {Association for Computational Linguistics},
  pages     = {69--72},
  url       = {http://www.aclweb.org/anthology/P06-4018},
  doi       = {10.3115/1225403.1225421}
}