GOMILKO, A. M.; PIVOVARCHIK, V. N. Inverse Sturm-Liouville problem on a figure-eight graph. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 60, n. 9, p. 1168–1188, 2008. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3235. Acesso em: 6 dec. 2025.