DerechV. D. “On Permutable Congruences on Antigroups of Finite Rank”. Ukrains’kyi Matematychnyi Zhurnal 56, no. 3 (March 25, 2004): 346-351. Accessed November 22, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/3758.