TAYSTRUK, O.; PIVOVARCHIK, V. N. Spectral problem for a graph of symmetric Stieltjes strings. Methods of Functional Analysis and Topology, [S. l.], v. 20, n. 2, p. 164–174, 2014. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/576. Acesso em: 15 dec. 2025.