BurtnyakI., ChernegaI., HladkyiV., LabachukO., and NovosadZ. “Application of Symmetric Analytic Functions to Spectra of Linear Operators”. Carpathian Mathematical Publications 13, no. 3 (December 11, 2021): 701-710. Accessed September 26, 2023. https://journals.pnu.edu.ua/index.php/cmp/article/view/5563.