@TechReport{bauer+:comptr,
  author =       {Lujo Bauer and Jarred Ligatti and David Walker},
  title =        {A Calculus for Composing Security Policies},
  institution =  {Princeton University},
  year =         {2002},
  number =       {TR-655-02},
  month =        aug,
  url =		 {http://www.cs.princeton.edu/~jligatti/papers/TR-655-02.pdf}
}