EFFICIENT LITERATURE RESEARCH BASED ON SEMANTIC TAGNETS - Implemented and Evaluated for a German Text-corpus Topics: Accessibility Issues and Technology; Digital Libraries; Metadata and Metamodeling; Multimedia and User Interfaces; Ontology and the Semantic Web; Searching and Browsing; Usability and Ergonomics In Proceedings of the 6th International Conference on Web Information Systems and Technology - Volume 2: WEBIST, 48-54, 2010 , Valencia, Spain