@InProceedings{GunterMS04,
  author =  {Carl A. Gunter and Michael J. May and Stuart Stubblebine},
  title =    {A Formal Privacy System and its Application to Location Based Services},
  booktitle =	{Privacy Enhancing Technologies ({PET} '04)},
  year =    2004,
  address = {Toronto},
  month =   {May},
}