# zbMATH — the first resource for mathematics

In an earlier paper [Abstr. Appl. Anal. 2005, No. 7, 767–790 (2005; Zbl 1104.47026)], the authors gave a construction of a class of selfadjoint operators with bounded inverses obtained as perturbations of a given selfadjoint operator $$A$$. Now they consider the case where the unperturbed operator is $$A^2$$ and study some special properties of their construction for this operator. Examples of integro-differential operators obtained this way are given.