J. Illig, B. Roth, and D. Klakow. Proceedings of the 14th Conference of the European Chapter of the Association for Computational Linguistics, volume 2: Short Papers, page 100--105. Gothenburg, Sweden, Association for Computational Linguistics, (April 2014)
A. Blessing, and H. Schütze. Proceedings of the 21st ACM international conference on Information and knowledge management, page 1123--1132. New York, NY, USA, ACM, (2012)