Cuong, Bui Cong. “Pythagorean Picture Fuzzy Sets (PPFS), Part 2- Some Main Picture Logic Operators on PPFS and Some Picture Inference Processes in PPF Systems”. Journal of Computer Science and Cybernetics 38, no. 1 (March 20, 2022): 1–14. Accessed December 5, 2025. https://vjs.ac.vn/jcc/article/view/15992.