Samoilenko, A. M., and Yu. V. Teplinsky. “On Decomposability of Countable Systems of Differential Equations”.
Ukrains’kyi Matematychnyi Zhurnal 45, no. 10 (October 25, 1993): 1424–1432. Accessed April 14, 2025.
https://umj.imath.kiev.ua/index.php/umj/article/view/5947.