U. Callmeier, A. Eisele, U. Schäfer, and M. Siegel. Proceedings of the 4th International Conference on Language Resources and Evaluation (LREC 2004), Lisbon, Portugal, page 1205-1208. European Language Resources Association (ELRA), (2004)
C. Cattuto, D. Benz, A. Hotho, and G. Stumme. The Semantic Web -- ISWC 2008: 7th International Semantic Web Conference, Karlsruhe, Germany, volume 5318 of Lecture Notes in Computer Science, Springer, Berlin, (2008)