G. Ifrim, M. Theobald, и G. Weikum. Proceedings of the 22nd International Conference on Machine Learning - Learning in Web Search (LWS 2005), стр. 18--26. Bonn, Germany, (2005)
M. Sanderson, и W. Croft. Proceedings of the 22nd Annual International ACM SIGIR Conference on Research and Development in Information Retrieval, SIGIR'99, стр. 206--213. (1999)