@INPROCEEDINGS{Bowers2007,
  author = {Kevin D. Bowers and Lujo Bauer and Deepak Garg and Frank Pfenning
	and Michael K. Reiter},
  title = {Consumable Credentials in Logic-Based Access-Control Systems},
  booktitle = {Proceedings of the 14th Annual Network and Distributed System Security
	Symposium (NDSS '07)},
  year = {2007},
  address = {San Diego, California},
  month = {February}
}