A. Hotho, R. Jäschke, C. Schmitz, and G. Stumme. Proc. First International Conference on Semantics And Digital Media Technology (SAMT), volume 4306 of LNCS, page 56-70. Heidelberg, Springer, (December 2006)
Y. Yao. Proceedings of 2004 Annual Meeting of the North American Fuzzy Information Processing Society(NAFIPS 2004),IEEE Catalog Number: 04 TH 8736, page 796-801. (2004)