@inproceedings{levy06tregex,
 author = {Roger Levy and Galen Andrew},
 year = 2006,
 title = {Tregex and Tsurgeon: tools for querying and manipulating tree data structures},
 booktitle = {5th International Conference on Language Resources and
                 Evaluation (LREC 2006)},
 pages = {2231--2234}
}