Patrick Doherty Andrzej Skowron Witold Lukaszewicz Andrzej Szalas 2003 57 Fundam. Inform. 2-4 http://iospress.metapress.com/openurl.asp?genre=article&issn=0169-2968&volume=57&issue=2&spage=i db/journals/fuin/fuin57.html#DohertySLS03