Harizanov С. Preface. Mathematics and Education in Mathematics, [S. l.], v. 54, p. 005–006, 2025. DOI: 10.55630/mem.2025.54.005-006. Disponível em: https://smb.math.bas.bg/mem/index.php/memjournal/article/view/176. Acesso em: 5 oct. 2026.