D. Arthur, и S. Vassilvitskii. SODA '07: Proceedings of the eighteenth annual ACM-SIAM symposium on Discrete algorithms, стр. 1027--1035. Philadelphia, PA, USA, Society for Industrial and Applied Mathematics, (2007)
W. Xu, X. Liu, и Y. Gong. SIGIR '03: Proceedings of the 26th annual international ACM SIGIR conference on Research and development in informaion retrieval, стр. 267--273. New York, NY, USA, ACM, (2003)