N. Fuhr, и K. Großjohann. Proceedings of the 24th Annual International ACM SIGIR Conference on Research and Development in Information Retrieval, стр. 172-180. ACM Press, (2001)
F. Jiang, и M. Littman. Proceedings of the Seventeenth International Conference on Machine Learning, стр. 423-430. Morgan Kaufmann Publishers Inc., (2000)