P. Cimiano, A. Hotho, und S. Staab. ECAI 2004 Proceedings of the 16th European Conference on Artificial Intelligence, 22 - 27 August, Valencia, Spain, Seite 435-439. IOS Press, (2004)
H. Yang, und J. Callan. Proceedings of the 47th Annual Meeting of the Association for Computational Linguistics (ACL2009), Seite 271–279. Singapore, (August 2009)