Shaocheng Tong Changying Li Yongming Li 0002 Fuzzy adaptive observer backstepping control for MIMO nonlinear systems. 2755-2775 2009 160 Fuzzy Sets Syst. 19 https://doi.org/10.1016/j.fss.2009.03.008 db/journals/fss/fss160.html#TongLL09