P. Knees, T. Pohle, M. Schedl, D. Schnitzer, und K. Seyerlehner. Advances in information retrieval. Proceedings of th 30th European Conference on IR Research, ECIR 2008, Seite 627--631. Heidelberg, Springer, (2008)
E. Jensen, S. Beitzel, O. Frieder, und A. Chowdhury. Special interest tracks and posters of the 14th international conference on World Wide Web, Seite 1176--1177. New York, NY, USA, ACM, (2005)