@InProceedings{li:2009:EMNLP,
  author    = {Li, Xiao},
  title     = {On the Use of Virtual Evidence in Conditional Random Fields},
  booktitle = {Proceedings of the 2009 Conference on Empirical Methods in Natural Language Processing},
  month     = {August},
  year      = {2009},
  address   = {Singapore},
  publisher = {Association for Computational Linguistics},
  pages     = {1289--1297},
  url       = {http://www.aclweb.org/anthology/D/D09/D09-1134}
}