Ralf Klamma Mohamed Amine Chatti Erik Duval Hans G. K. Hummel Ebba Thora Hvannberg Milos Kravcik Effie Law Ambjörn Naeve Peter Scott Social Software for Life-long Learning. 72-83 2007 10 Educational Technology & Society 3 http://www.ifets.info/abstract.php?art_id=770 db/journals/ets/ets10.html#KlammaCDHHKLNS07