Yakovets, V.P. (1998) “On the structure of the general solution of a degenerate linear system of second-order differential equations”,
Ukrains’kyi Matematychnyi Zhurnal, 50(2), pp. 292–298. Available at:
https://umj.imath.kiev.ua/index.php/umj/article/view/4962 (Accessed: 16 April 2025).