Adam Kasperski Pawel Zielinski Determining Unfuzzy Nondominated Solutions in Combinatorial Optimization Problems with Fuzzy Costs. 1-6 2007 FUZZ-IEEE http://dx.doi.org/10.1109/FUZZY.2007.4295381 conf/fuzzIEEE/2007 db/conf/fuzzIEEE/fuzzIEEE2007.html#KasperskiZ07