Motornyi, V. P. “On the Exact Constants in Hardy – Littlewood Inequalities”. Ukrains’kyi Matematychnyi Zhurnal 69, no. 12 (December 25, 2017): 1625–1632. Accessed December 5, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/1809.