@TechReport{	  sevinc.ea:controlling:2006,
  abstract	= {Current access-control systems for documents suffer from
		  one or more of the following limitations: they are
		  coarse-grained, limited to XML documents, or unable to
		  maintain control over copies of documents once they are
		  released by the system. We present a formal model of a
		  system that overcomes all of these restrictions. It is very
		  fine-grained, supports a general class of documents, and
		  provides a foundation for usage control.},
  address	= {8092 Zurich, Switzerland},
  author	= {Paul E. Sevin\c{c} and David Basin},
  institution	= {ETH Zurich},
  language	= {USenglish},
  month		= {May},
  number	= 517,
  pdf		= {papers/2006/ETRICSTR.pdf},
  title		= {Controlling Access to Documents: A Formal Access Control
		  Model},
  url		= {http://www.inf.ethz.ch/research/disstechreps/techreports/show?serial=517&lang=en}
		  ,
  year		= 2006,
  user		= {psevinc}
}