Hlova, T.Ya., and P.V. Filevych. “On an Estimation of R-Type of Entire Dirichlet Series and Its Exactness”. Carpathian Mathematical Publications 5, no. 2 (December 30, 2013): 208–216. Accessed April 25, 2024. https://journals.pnu.edu.ua/index.php/cmp/article/view/1311.