Boichuk ОA, Khrashchevskaya RF. Weakly nonlinear boundary-value problems for differential systems with pulse influence. Ukr. Mat. Zhurn. [Internet]. 1993 Feb. 25 [cited 2025 Apr. 9];45(2):221–225. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/5801