ASHYRALYEV, Allaberen; SADYBEKOV, Makhmud A. Preface. Bulletin of the Karaganda University. Mathematics Series, [S. l.], v. 99, n. 3, p. 4, 2020. Disponível em: http://mts.buketov.edu.kz/index.php/mathematics-vestnik/article/view/451. Acesso em: 5 sep. 2025.