Sobchuk, V. V., and I. O. Zelenska. “Construction of Asymptotics of the Solution for a System of Singularly Perturbed Equations by the Method of Essentially Singular Functions”. Bulletin of Taras Shevchenko National University of Kyiv. Physical and Mathematical Sciences, no. 2, Dec. 2023, pp. 184-92, doi:10.17721/1812-5409.2023/2.34.