Fardigola, L. V. “Nonlocal Two-Point Boundary-Value Problems in a Layer With Differential Operators in the Boundary Condition”. Ukrains’kyi Matematychnyi Zhurnal 47, no. 8 (August 25, 1995): 1122–1128. Accessed April 11, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/5508.