U. Callmeier, A. Eisele, U. Schäfer, и M. Siegel. Proceedings of the 4th International Conference on Language Resources and Evaluation (LREC 2004), Lisbon, Portugal, стр. 1205-1208. European Language Resources Association (ELRA), (2004)
G. Buscher, A. Dengel, и L. van Elst. SIGIR '08: Proceedings of the 31st Annual International ACM SIGIR Conference on Research and Development in Information Retrieval, Singapore, стр. 387-394. (2008)