Georgios K. Giannikis Aspassia Daskalopulu The Representation of e-Contracts as Default Theories. 963-973 2007 conf/ieaaie/2007 IEA/AIE http://dx.doi.org/10.1007/978-3-540-73325-6_96 db/conf/ieaaie/ieaaie2007.html#GiannikisD07