1. R. W. Conway, W. L. Maxwell and H. L. Morgan,On the implementation of security measures in information systems, Comm. ACM, Vol. 15, No. 4, (1972), pp. 211–220.
2. P. J. Denning,An Undergraduate Course on Operating Systems Principles, inReport of the Cosine Comm of the Commission on Education, National Academy of Engineering, Washington, D.C. (1971).
3. P. J. Denning,Third generation computer systems, Computing Surveys, Vol. 3, No. 4, (1971), pp. 175–216.
4. G. S. Graham and P. L. Denning,Protection — principles and practice, Proc. Spring Jt. Computer Conference, Vol. 40, AFIPS Press, Montvale, N.J., (1972), pp. 417–429.
5. D. E. Knuth,The Art of Computer Programming, Vol. 1: Fundamental Algorithms, Second edition, Addison-Wesley, Reading, Massachusetts, (1973).