1. Cryptographic solution to a problem of access control in a hierarchy;Akl;ACM Trans. Comput. Syst.,1983
2. Checking classification constraints for consistency and completeness;Akl,1987
3. Security kernels: a solution or a problem?;Ames,1981
4. Design of a privacy oriented information system—final report of the Projekgruppe DORIS;Biskup,1986
5. Analysis of the privacy model for the information system DORIS;Biskup,1988