Degano, Pierpaolo and De Nicola, Rocco and Montanari, Ugo Partial orderings descriptions and observations of nondeterministic concurrent processes. In: Linear Time, Branching Time and Partial Order in Logics and Models for Concurrency (REX Workshop 1988). Lecture Notes in Computer Science, 354 . Springer, pp. 438-466. ISBN 3-540-51080-X (1988)