O. V. Vyatchaninov and M. F. Gorodnii, “On the boundedness of one recurrent sequence in a banach space”, Ukr. Mat. Zhurn., vol. 61, no. 9, pp. 1293–1296, Sep. 2009, Accessed: Feb. 17, 2026. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/3100