Hembars’kaS. B., and ZadereiP. V. “On the Absolute Convergence of Power Series”. Ukrains’kyi Matematychnyi Zhurnal 51, no. 5 (May 25, 1999): 594–602. Accessed October 6, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/4647.