@inproceedings{conf/tapp/BunemanCK12,
  title = "Hierarchical models of provenance",
  author = "Peter Buneman and James Cheney and Egor V. Kostylev",
  year = "2012",
  booktitle = "Proceedings of the 4th {USENIX} Workshop on the Theory and Practice of Provenance (TaPP 2012), Boston, Massachusetts, USA, June 14-15, 2012",
  publisher = "{USENIX} Association",
}