Klyus, I. S. and Ptashnik, B. I. (1999) “A multipoint problem for partial differential equations unresolved with respect to the higher time derivative”, Ukrains’kyi Matematychnyi Zhurnal, 51(12), pp. 1604–1613. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/4765 (Accessed: 17May2024).