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S. Hellmann, J. Lehmann, and S. Auer. Learning of OWL Class Expressions on Very Large Knowledge Bases and its Applications, chapter 5, IGI Global, (2011)
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.
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)