Zofia Matusiewicz Wladyslaw Homenda Operations on Balanced Fuzzy Sets. 1-6 2023 FUZZ https://doi.org/10.1109/FUZZ52849.2023.10309700 conf/fuzzIEEE/2023 db/conf/fuzzIEEE/fuzzIEEE2023.html#MatusiewiczH23