1. Fuzzy sets
2. Intuitionistic fuzzy sets
3. SmarandacheF. A unifying field in logics. Neutrosophy: neutrosophic probability set and logic. Rehoboth: American Research Press; 1999.
4. ZhangWR. Bipolar fuzzy sets and relations: a computational framework for cognitive modeling and multiagent decision analysis. In:NAFIPS/IFIS/NASA'94. Proceedings of the First International Joint Conference of The North American Fuzzy Information Processing Society Biannual Conference. The Industrial Fuzzy Control and Intellige; 1994:305‐309. IEEE. (December).
5. Some more results on bipolar fuzzy sets and bipolar fuzzy intersection graphs;Samanta S;J Fuzzy Math,2014