Mel’nik, T. A. “Aniterative Method for the Solution of Some Singularly Perturbed Cauchy Problems”. Ukrains’kyi Matematychnyi Zhurnal 49, no. 8 (August 25, 1997): 1055–1060. Accessed May 19, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/5100.