@InProceedings{levitan-gravano-hirschberg:2011:ACL-HLT2011,
  author    = {Levitan, Rivka  and  Gravano, Agustin  and  Hirschberg, Julia},
  title     = {Entrainment in Speech Preceding Backchannels.},
  booktitle = {Proceedings of the 49th Annual Meeting of the Association for Computational Linguistics: Human Language Technologies},
  month     = {June},
  year      = {2011},
  address   = {Portland, Oregon, USA},
  publisher = {Association for Computational Linguistics},
  pages     = {113--117},
  url       = {http://www.aclweb.org/anthology/P11-2020}
}