New Key Generation Algorithms for Multilevel Security. - Stephen J. MacKinnon; Selim G. Akl (S&P, 1983)

An Optimal Algorithm for Assigning Cryptographic Keys to Control Access in a Hierarchy. - Stephen J. MacKinnon; Peter D. Taylor; Henk Meijer; Selim G. Akl (IEEE Trans. Computers, 1985)