Terence R. Smith Dan Ancona Olha A. Buchel Michael Freeston W. Heller R. Nottrott Tim Tierney Alex Ushakov The ADEPT Concept-Based Digital Learning Environment. 300-312 2003 conf/ercimdl/2003 ECDL db/conf/ercimdl/ecdl2003.html#SmithABFHNTU03 http://dx.doi.org/10.1007/b11967