Levchuk, V. M. (2017) “On conditionless bases of the kernels generated by differential equations of the second order”, Ukrains’kyi Matematychnyi Zhurnal, 69(3), pp. 332-347. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/1700 (Accessed: 28April2024).