1. Intuitionistic fuzzy sets
2. New operations defined over the intuitionistic fuzzy sets
3. Operators over interval valued intuitionistic fuzzy sets
4. Interval valued intuitionistic fuzzy sets
5. K.T. Atanassov, D. Mavrov and V. Atanassova, ”Intercriteria Decision Making: A New Approach for Multicriteria Decision Making, Based on Index Matrices and Intuitionistic Fuzzy Sets,” Issues in IFSs and GNs, Vol. 11, pp. 1–8, 2014.