TAYSTRUK, O.; PIVOVARCHIK, V. N. On characteristic functions of operators on equilateral graphs. Methods of Functional Analysis and Topology, [S. l.], v. 18, n. 2, p. 189–197, 2012. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/514. Acesso em: 16 dec. 2025.