Rusev, Peter. “Zeroes of Polynomials and Entire Functions in the Works of N. Obreshkoff”. Ann. Sofia Univ. Fac. Math. and Inf. 89 (December 12, 1997): 37–46. Accessed November 21, 2024. https://stipendii.uni-sofia.bg/index.php/fmi/article/view/353.