Metric Pomset Semantics for a Concurrnt Language with Recursion. - J. W. de Bakker; J. H. A. Warmerdam (Semantics of Systems of Concurrent Processes, 1990)

Four Domains for Concurrency. - J. W. de Bakker; J. H. A. Warmerdam (Theor. Comput. Sci., 1991)