Kenzhebaev, K. K., and V. N. Laptinskii. “Analytic Representation of Periodic Solutions of Linear Differential Systems”. Ukrains’kyi Matematychnyi Zhurnal 49, no. 5 (May 25, 1997): 731–735. Accessed February 17, 2026. https://umj.imath.kiev.ua/index.php/umj/article/view/5057.