E. Weippl, G. Quirchmayr:
"Revisiting Mandatory Access Control: Improving the security of e-learning systems";
in: "Proceedings of International Conference on Communication and Computer Networks (CCN 2004)", issued by: IASTED; ACTA Press, 2004, ISBN: 0-88986-431-4.
http://aleph.ub.tuwien.ac.at/F?base=tuw01&func=find-c&ccl_term=AC04968629