P. Heim, S. Hellmann, J. Lehmann, S. Lohmann, and T. Stegemann. Proceedings of the 3rd International Conference on Semantic and Media Technologies (SAMT), volume 5887 of Lecture Notes in Computer Science, page 182--187. Springer, (2009)
S. Hellmann, C. Stadler, J. Lehmann, and S. Auer. Proc. of 8th International Conference on Ontologies, DataBases, and Applications of Semantics (ODBASE), volume 5871 of Lecture Notes in Computer Science, page 1209--1223. (2009)
S. Hellmann, J. Lehmann, S. Auer, and M. Nitzschke. EKAW, page 446--449. (2012)published at EKAW, preprint http://jens-lehmann.org/files/2012/ekaw\_nif\_combinator.pdf.