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