Boyko, O. P.; Martynyuk, O. M.; Pivovarchik, V. N. On the Second Largest Multiplicity of Eigenvalues for the Stieltjes String Spectral Problem on Trees. MFAT 2021, 27 (3), 217-226. https://doi.org/https://doi.org/10.31392/MFAT-npu26_3.2021.03.