1. Aceto, L., De Nicola, R. and Fantechi, A. Testing Equivalences for Event Structures, in Mathematical Models for the Semantics of Parallelism (M. Venturini Zilli, Ed.), LNCS, 280, Springer-Verlag, Heidelberg, 1987, pp. 1–20.
2. Austry, D. and Boudol, G. Alg`ebre de Processus et Synchronization, Theoret. Comput. Sci., 30, 1 (1984), 91–131.
3. Boudol, G. and Castellani, I. On the Semantics of Concurrency: Partial Orders and Transition Systems, in Proc. TAPSOFT-CAAP '87, Lecture Notes in Computer Science, 249, Springer-Verlag, Heidelberg, 1987, pp. 123–137.
4. Castellani,I. Franceschi,P. and Montanari,U. Labeled Event Structures: A Model for Observable Concurrency, in Formal Description of Programming Concepts II (D. Bijørner, Ed.), North Holland, Amsterdam, 1983, pp. 383–400.
5. Degano,P., De Nicola,R. and Montanari,U. Observational Equivalences for Concurrency Models, in Formal Description of Programming Concepts III (M. Wirsing, Ed.), North Holland, Amsterdam, 1987, pp. 105–132.