Korol' II, Perestyuk NA. Once again on the Samoilenko numerical-analytic method of successive periodic approximations. Ukr. Mat. Zhurn. [Internet]. 2006 Apr. 25 [cited 2025 Dec. 6];58(4):472–488. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/3468