Applications of category theory to fuzzy subsets / ed. by Stephen Ernest Rodabaugh, Erich Peter Klement and Ulrich HöhleMathematics of fuzzy sets : logic, topology, and measure theory / ed. by Ulrich Höhle and Stephen Ernest RodabaughTopological and algebraic structures in fuzzy sets : a handbook of recent developments in the mathematics of fuzzy sets / ed. by Stephen Ernest Rodabaugh and Erich Peter Klement