U. Schäfer, B. Kiefer, C. Spurk, J. Steffen, and R. Wang. Proceedings of the ACL-HLT 2011 System Demonstrations, page 7--13. Portland, Oregon, Association for Computational Linguistics, (June 2011)
A. Bernstein, E. Kaufmann, A. Göhring, and C. Kiefer. International Semantic Web Conference, volume 3729 of Lecture Notes in Computer Science, page 112-126. Springer, (2005)