Kees Middelburg Process Algebra with Nonstandard Timing. 55-77 2002 53 Fundam. Inform. 1 http://iospress.metapress.com/openurl.asp?genre=article&issn=0169-2968&volume=53&issue=1&spage=55 db/journals/fuin/fuin53.html#Middelburg02