Ingo Dahn Management of Informal Mathematical Knowledge ? Lessons Learned from the Trial-Solution Project. 29-43 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2730&spage=29 2002 conf/icm/2002ei Electronic Information and Communication in Mathematics db/conf/icm/icm2002ei.html#Dahn02