Radzievskaya, E.I. and Radzievskii, G.V. (2005) “On One Extremal Problem for a Seminorm on the Space $l_1$ with Weight”, Ukrains’kyi Matematychnyi Zhurnal, 57(7), pp. 1002–1006. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/3659 (Accessed: 5 December 2025).