GERGELITSOVÁ, Šárka; HOLAN, T. Problém s poštou. Matematika–Fyzika–Informatika, [S. l.], v. 28, n. 4, p. 250–253, 2019. Disponível em: http://158.194.80.143/index.php/mfi/article/view/466. Acesso em: 13 led. 2025.