Châu, Trần Thọ. “Fuzzy Petri Nets and a Necessary Condition of Law of Contraposition in Fuzzy Logic”. Journal of Computer Science and Cybernetics 16, no. 3 (April 11, 2013): 23–31. Accessed December 5, 2025. https://vjs.ac.vn/jcc/article/view/2904.