D. Cutting, D. Karger, J. Pedersen, и J. Tukey. SIGIR '92: Proceedings of the 15th annual international ACM SIGIR conference on Research and development in information retrieval, стр. 318--329. New York, NY, USA, ACM Press, (1992)
G. Frahling, и C. Sohler. SCG '06: Proceedings of the twenty-second annual symposium on Computational geometry, стр. 135--143. New York, NY, USA, ACM, (2006)