@InProceedings{Petrov-Klein:2007:Learning,
  title     = {Learning and Inference for Hierarchically Split {PCFG}s},
  author    = {Slav Petrov and Dan Klein},
  booktitle = {Proceedings of AAAI (Nectar Track)},
  year      = {2007},
  url       = {http://www.petrovi.de/data/aaai2007.pdf},
}