U. Callmeier, A. Eisele, U. Schäfer, and M. Siegel. Proceedings of the 4th International Conference on Language Resources
and Evaluation (LREC), Lisbon, Portugal, (2004)
P. Buitelaar, P. Cimiano, S. Racioppa, and M. Siegel. Proceedings of the 5th International Conference on Language Resources
and Evaluation (LREC), page 2321--2324. ELRA, (2006)