E. Weippl:
"Non-repudiation and audits in e-learning";
Talk: Proceedings of E-Learn, Vancouver, Canada (invited); 2005-10-24 - 2005-10-28; in: "Proceedings of E-Learn 2005", (2005), 1785 - 1790.
http://aleph.ub.tuwien.ac.at/F?base=tuw01&func=find-c&ccl_term=AC05936427