J. Pedro, und S. Siersdorfer. WWW '09: Proceedings of the 18th international conference on World wide web, Seite 771--780. New York, NY, USA, ACM, (2009)
D. Skoutas, und M. Alrifai. In Proc. of 20th ACM international conference on Information and knowledge management (CIKM '11), ACM, New York, NY, USA, 221-230., (2011)
A. Stent, und A. Loui. Proceedings of the 24th annual international ACM SIGIR conference on Research and development in information retrieval, Seite 59--65. New York, NY, USA, ACM, (2001)
W. Eger, und G. Kesper. Schriftenreihe Naturschutz in Waldeck-Frankenberg NABU Waldeck-Frankenberg, Postfach 33 34547 Edertal, (2011)Literaturverz. S. 475 - 483.
S. Ahern, M. Naaman, R. Nair, und J. Yang. JCDL '07: Proceedings of the 7th ACM/IEEE-CS joint conference on Digital libraries, Seite 1-10. New York, NY, USA, ACM, (2007)