GorodniiM. F. (1993) “Existence of solutions of boundary-value problems corresponding to a certain difference equation in a Banach space”, Ukrains’kyi Matematychnyi Zhurnal, 45(3), pp. 431–435. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/5826 (Accessed: 24November2024).