A. Hotho, R. Jäschke, C. Schmitz, and G. Stumme. Proceedings of the 3rd European Semantic Web Conference, volume 4011 of LNCS, page 411-426. Budva, Montenegro, Springer, (June 2006)
B. Krause, C. Schmitz, A. Hotho, and G. Stumme. LWA, volume 448 of Technical Report, page 61-68. Department of Computer Science, University of Würzburg, Germany, (2008)