Yannis Tzitzikas Vassilis Christophides Giorgos Flouris Dimitris Kotzinos Hannu Markkanen Dimitris Plexousakis Nicolas Spyratos Trialogical E-Learning and Emergent Knowledge Artifacts. 703-708 2006 conf/ectel/2006 EC-TEL http://dx.doi.org/10.1007/11876663_76 db/conf/ectel/ectel2006.html#TzitzikasCFKMPS06