TAWFIQ, L. N. M.; SHIHAB, R. H. The Commutator of Two Fuzzy Subsets. Ibn AL-Haitham Journal For Pure and Applied Sciences, Baghdad, Iraq., v. 25, n. 2, 2017. Disponível em: https://www.jih.uobaghdad.edu.iq/index.php/j/article/view/643. Acesso em: 1 may. 2025.