V. F. Zhuravlev, “Weakly perturbed operator equations in Banach spaces”, Ukr. Mat. Zhurn., vol. 69, no. 6, pp. 751–764, Jun. 2017, Accessed: Apr. 23, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/1733