Stasyuk, Ya.Z., and O.B. Skaskiv. “On the Equivalence of the Sum and the Maximal Term of the Dirichlet Series Absolutely Convergent in the Half-Plane”. Carpathian Mathematical Publications, vol. 1, no. 1, June 2009, pp. 100-6, https://ktipe.pnu.edu.ua/index.php/cmp/article/view/4007.