Олейник, Елена В. “The Study of Solutions of a Class of Nonlinear Systems”. Visnyk of V. N. Karazin Kharkiv National University. Ser. Mathematics, Applied Mathematics and Mechanics 820 (December 29, 2015): 34-46. Accessed April 30, 2024. https://periodicals.karazin.ua/mech_math/article/view/4761.