R. Wetzker, C. Zimmermann, C. Bauckhage, and S. Albayrak. Proceedings of the third ACM international conference on Web search and data mining, page 71--80. New York, NY, USA, ACM, (2010)
R. Wetzker, W. Umbrath, and A. Said. ESAIR '09: Proceedings of the WSDM '09 Workshop on Exploiting Semantic Annotations in Information Retrieval, page 25--29. New York, NY, USA, ACM, (2009)