Norbert E. Fuchs Uta Schwertel Reasoning in Attempto Controlled English. 174-188 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2901&spage=174 2003 conf/ppswr/2003 PPSWR db/conf/ppswr/ppswr2003.html#FuchsS03