BOYKO, O. P.; MARTINYUK, O. M.; PIVOVARCHIK, V. N. On the relationship between the multiplicities of eigenvalues in finite- and infinite-dimensional problems on graphs. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 69, n. 4, p. 445–455, 2017. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/1708. Acesso em: 5 dec. 2025.