ULBRIKHT, O.I.; URKEN, G.A. On closure operators of Jonsson sets. Bulletin of the Karaganda University. Mathematics Series, [S. l.], v. 114, n. 2, p. 211–220, 2024. DOI: 10.31489/2024m2/211-220. Disponível em: https://mts.buketov.edu.kz/index.php/mathematics-vestnik/article/view/718. Acesso em: 5 jul. 2025.