“The construction of asymptotic solutions of a singularly perturbed linear system of differential equations with an irregular singular point in the case where the main matrix has multiple spectrum” (2008) Neliniini Kolyvannya, 11(1), pp. 128–144. Available at: https://twinhead.imath.kiev.ua/index.php/nosc/article/view/467 (Accessed: 21 January 2026).