Manfred Widera Barbara Messing Gabriele Kern-Isberner Malte Isberner Christoph Beierle An Extendable System for the Specification and Generation of Interactive Self-tests. 316-321 2006 conf/edutainment/2006 Edutainment http://dx.doi.org/10.1007/11736639_41 db/conf/edutainment/edutainment2006.html#WideraMKIB06