Mel’nik, T. A. “Asymptotics of a Solution of a Discontinuous Singularly Perturbed Cauchy Problem”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 46, no. 11, Nov. 1994, pp. 1502–1508, https://umj.imath.kiev.ua/index.php/umj/article/view/5589.