Yeshkeyev, A.R. “On Jonsson Varieties and Quasivarieties”. Bulletin of the Karaganda University. Mathematics Series 104, no. 4 (December 30, 2021): 151–157. Accessed September 4, 2025. https://mts.buketov.edu.kz/index.php/mathematics-vestnik/article/view/494.