A. A. Martynyuk, “On one attribute of solution stability for systems of non-linear differential equations ”, Ukr. Mat. Zhurn., vol. 23, no. 2, pp. 253–257, Feb. 1971, Accessed: Dec. 06, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/8510