Green operator of a singularly perturbed matrix periodic boundary value problem for Lyapunov equation. Neliniini Kolyvannya, [S. l.], v. 29, n. 1, p. 77–88, 2026. DOI: 10.3842/nosc.v29i1.1532. Disponível em: https://nosc.imath.kiev.ua/index.php/nosc/article/view/1208. Acesso em: 25 aug. 2026.