Horodets’kyi, V. V., and O. V. Martynyuk. 2014. “Nonlocal Problem Multipoint in Time for the Evolutionary Equations With Pseudo-Bessel Operators With Variable Symbols”. Ukrains’kyi Matematychnyi Zhurnal 66 (2), 159–175. https://umj.imath.kiev.ua/index.php/umj/article/view/2120.