Gorodnii, M. F. “$l_p$-Solutions of One Difference Equation in a Banach Space”. Ukrains’kyi Matematychnyi Zhurnal 55, no. 3 (March 25, 2003): 425-430. Accessed May 19, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/3916.