Costas Courcoubetis, Susanne Graf, Joseph Sifakis. An Algebra of Boolean Processes. In Kim Guldstrand Larsen, Arne Skou, editors, Computer Aided Verification, 3rd International Workshop, CAV 91, Aalborg, Denmark, July, 1-4, 1991, Proceedings. Volume 575 of Lecture Notes in Computer Science, pages 454-465, Springer, 1991.