Pivovarchik, V., and A. Dudko. “Inverse Spectral Problem for a Star Graph of Stieltjes Strings With Prescribed Numbers of Masses on the Edges”. Ukrains’kyi Matematychnyi Zhurnal 73, no. 1 (January 20, 2021): 47 - 60. Accessed April 26, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/2398.