Kazuo Tanaka Hiroto Yoshida Hiroshi Ohtake Hua O. Wang A Sum of Squares Approach to Stability Analysis of Polynomial Fuzzy Systems. 4071-4076 2007 ACC https://doi.org/10.1109/ACC.2007.4282579 conf/amcc/2007 db/conf/amcc/acc2007.html#TanakaYOW07