1. Cryptographic solution to a problem of access control in a hierarchy;Akl;ACM Trans. Comput. Syst.,1983
2. A model for multilevel security in computer networks;Lu,1988
3. Specifications for multi-level security and a hook-up property;McCullough,1987
4. A security policy and formal top level specification for a multi-level secure local area network;McHugh,1986
5. Scomp: a solution to multilevel security problem;Fraim,1983