Ptashnik, B. I., and L. P. Sylyuha. “Multipoint Problem for Typeless Systems of Differential Equations With Constant Coefficients”. Ukrains’kyi Matematychnyi Zhurnal 49, no. 9 (September 25, 1997): 1236–1249. Accessed May 21, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/5123.