Abildayeva, A. D., and D. S. Dzhumabaev. “Properties of the Isolated Solutions Bounded on the entire axis for a System of Nonlinear Ordinary Differential Equations”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 68, no. 8, Aug. 2016, pp. 1132-8, https://umj.imath.kiev.ua/index.php/umj/article/view/1907.