Q. Liu, R. Safavi-Naini, and N. Sheppard. ACSW Frontiers '03: Proceedings of the Australasian information security workshop conference on ACSW frontiers 2003, page 49--58. Darlinghurst, Australia, Australia, Australian Computer Society, Inc., (2003)
S. Etalle, and W. Winsborough. SACMAT '07: Proceedings of the 12th ACM symposium on Access control models and technologies, page 11--20. New York, NY, USA, ACM Press, (2007)