Makhkamov KS. On the exact degree of complexity of a class of operator equations of the second kind in a Hilbert space. Ukr. Mat. Zhurn. [Internet]. 1994 Jul. 25 [cited 2025 Apr. 7];46(7):893–903. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/5681