Jerry M. Mendel Hongwei Wu Type-2 Fuzzistics for Nonsymmetric Interval Type-2 Fuzzy Sets: Forward Problems. 916-930 2007 15 IEEE T. Fuzzy Systems 5 http://dx.doi.org/10.1109/TFUZZ.2006.889959 db/journals/tfs/tfs15.html#MendelW07a