1. BURNS, A. and WELLINGS, A. (1990): Real-Time Systems and their Programming Languages, Addison-Wesley.
2. COOMBES, A. (1990): An Interval Logic for Modelling Time in Z, Technical report, University of York, Dept. Computer Science.
3. DELISLE, N. and GARLAN, D. (1989): Formally Specifying Electronic Instruments, ACM SIGSOFT Eng. Notes, 14(3), pp. 242–248.
4. DILLER, A. (1990): Z: An Introduction to Formal Methods, John Wiley and Sons.
5. DUKE, R. and SMITH, G. (1989): Temporal Logic and Z Specifications, The Australian Computer Journal, 21(2), pp. 62–66.