Leeratanavalee, Sorasak, and Jukkrit Daengsaen. “Green’s Relations on Regular Elements of Semigroup of Relational Hypersubstitutions for Algebraic Systems of Type ((m), (n))”. Tamkang Journal of Mathematics 53, no. 2 (May 1, 2022): 127–146. Accessed April 19, 2024. https://journals.math.tku.edu.tw/index.php/TKJM/article/view/3436.