X. Lam, T. Vu, T. Le, и A. Duong. Proceedings of the 2nd international conference on Ubiquitous information management and communication, стр. 208--211. New York, NY, USA, ACM, (2008)
A. Schein, A. Popescul, L. Ungar, и D. Pennock. Proceedings of the 25th annual international ACM SIGIR conference on Research and development in information retrieval, стр. 253--260. New York, NY, USA, ACM, (2002)