Jon A. Solworth Robert H. Sloan A Layered Design of Discretionary Access Controls with Decidable Safety Properties. 56- 2004 conf/sp/2004 IEEE Symposium on Security and Privacy http://csdl.computer.org/comp/proceedings/sp/2004/2136/00/21360056abs.htm db/conf/sp/sp2004.html#SolworthS04