C. Schmitz, A. Hotho, R. Jäschke, and G. Stumme. Data Science and Classification: Proc. of the 10th IFCS Conf., page 261--270. Berlin, Heidelberg, Springer, (2006)
A. Hotho, R. J�schke, C. Schmitz, and G. Stumme. The Semantic Web: Research and Applications, volume 4011 of LNAI, page 411-426. Heidelberg, Springer, (June 2006)