“Asymptotics of a Generalized Solution of Linear Singularly Perturbed Systems of Higher Order Differential Equations With Degenerations in the Case of Multiple Spectrum of Boundary Coupling of Matrices”. Neliniini Kolyvannya 17, no. 3 (September 29, 2014): 379–398. Accessed January 21, 2026. https://twinhead.imath.kiev.ua/index.php/nosc/article/view/751.