Radzievsky GV. Multiple minimality of the root vectors of polynomial operators bunch, perturbed by analytical operator-function $S (\lambda)$ с $S (\infty) = 0$ outside the circle . Ukr. Mat. Zhurn. [Internet]. 1988 Aug. 29 [cited 2025 Dec. 6];40(5):599-610. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/8808