Boyka Gradinarova Teodora Ivanova Bakardjieva Milena Gradinarova Some Aspects of Application of Software Agents in Information Retrieval in Virtual-Based Educational Environments. 315-319 2006 conf/ifip3/2006 Education for the 21st Century http://dx.doi.org/10.1007/978-0-387-34731-8_37 db/conf/ifip3/ifip3-2006.html#GradinarovaBG06