Ioannis Tsampoulatidis Dimitrios Tzovaras Michael G. Strintzis Ontology-Based E-government Thematic Services Based on Topic Maps. 569-580 http://dx.doi.org/10.1007/978-3-540-30470-8_70 2004 conf/otm/2004 OTM Workshops db/conf/otm/otm2004.html#TsampoulatidisTS04