John Derrick Eerke A. Boiten Proceedings of the REFINE 2005 Workshop, REFINE 2005, Guildford, UK, April 2005 REFINE Electronic Notes in Theoretical Computer Science 137 2 Elsevier 2005 https://www.sciencedirect.com/journal/electronic-notes-in-theoretical-computer-science/vol/137/issue/2 db/conf/refine/refine2005.html