@InProceedings{azuma-matsumoto:2011:EMNLP,
  author    = {Azuma, Ai  and  Matsumoto, Yuji},
  title     = {Multilayer Sequence Labeling},
  booktitle = {Proceedings of the 2011 Conference on Empirical Methods in Natural Language Processing},
  month     = {July},
  year      = {2011},
  address   = {Edinburgh, Scotland, UK.},
  publisher = {Association for Computational Linguistics},
  pages     = {628--637},
  url       = {http://www.aclweb.org/anthology/D11-1058}
}