BOYVALENKOV, P.; BOUYUKLIEVA, S. 80th birth anniversary of Acad. Stefan Dodunekov. Mathematics and Education in Mathematics, [S. l.], v. 55, p. 285–297, 2026. DOI: 10.55630/mem.2026.55.285-297. Disponível em: https://smb.math.bas.bg/mem/index.php/memjournal/article/view/243. Acesso em: 7 oct. 2026.