Radzievskii, G. V. (2003). Uniqueness of Solutions of Some Nonlocal Boundary-Value Problems for Operator-Differential Equations on a Finite Segment. Ukrains’kyi Matematychnyi Zhurnal, 55(7), 1006-1009. https://umj.imath.kiev.ua/index.php/umj/article/view/3976