@inproceedings{Suzuki:2003:ACL,
  author = {Suzuki, Jun  and  Hirao, Tsutomu  and  Sasaki, Yutaka  and  Maeda, Eisaku},
  title  = {Hierarchical Directed Acyclic Graph Kernel: Methods for Structured Natural Language Data},
  booktitle = {Proceedings of the 41st Annual Meeting of the Association for Computational Linguistics},
  editor = {Erhard Hinrichs and Dan Roth},
  url    = {http://www.aclweb.org/anthology/P03-1005.pdf},
  year   = 2003,
  pages  = {32--39}
}