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Alur R, Henzinger TA, Ho P. Automatic symbolic verification of embedded systems. In: 1993 Proceedings Real-Time Systems Symposium. IEEE; 1993:2-11. doi:10.1109/REAL.1993.393520 

Alur R, Courcoubetis C, Henzinger TA. Computing accumulated delays in real-time systems. In: 5th International Conference on Computer Aided Verification. Vol 697. Springer; 1993:181-193. doi:10.1007/3-540-56922-7_16

Alur R, Henzinger TA, Vardi M. Parametric real-time reasoning. In: Proceedings of the 25th Annual ACM Symposium on Theory of Computing. ACM; 1993:592-601. doi:10.1145/167088.167242