Petrovskii, Y. B. and Khoma, G. P. (1997) “The solvability of a boundary-value periodic problem”, Ukrains’kyi Matematychnyi Zhurnal, 49(2), pp. 302–308. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/5006 (Accessed: 19May2024).