Sarah Greenfield Francisco Chiclana Simon Coupland Robert John The collapsing method of defuzzification for discretised interval type-2 fuzzy sets. 2055-2069 2009 179 Inf. Sci. 13 http://dx.doi.org/10.1016/j.ins.2008.07.011 db/journals/isci/isci179.html#GreenfieldCCJ09