Kamont, Z. “Infinite Systems of Hyperbolic Functional Differential Equations”.
Ukrains’kyi Matematychnyi Zhurnal
55, no. 12 (December 25, 2003): 1678–1796. Accessed April 11, 2025.
https://umj.imath.kiev.ua/index.php/umj/article/view/4030
.