Stanislav Krajci Jana Krajciova Social Network and One-sided Fuzzy Concept Lattices. 1-6 2007 FUZZ-IEEE http://dx.doi.org/10.1109/FUZZY.2007.4295369 conf/fuzzIEEE/2007 db/conf/fuzzIEEE/fuzzIEEE2007.html#KrajciK07