et. al., Dr. D. Mrudula Devi. “A Characterization of Commutative Semigroups”. Turkish Journal of Computer and Mathematics Education (TURCOMAT) 12, no. 3 (April 11, 2021): 5150–5155. Accessed May 3, 2024. https://turcomat.org/index.php/turkbilmat/article/view/2065.