BOYKO, O. P.; MARTYNYUK, O. M.; PIVOVARCHIK, V. N. On the second largest multiplicity of eigenvalues for the Stieltjes string spectral problem on trees. Methods of Functional Analysis and Topology, [S. l.], v. 27, n. 3, p. 217–226, 2021. DOI: https://doi.org/10.31392/MFAT-npu26_3.2021.03. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/798. Acesso em: 16 dec. 2025.