1. S. G. Krein, Linear Equations in Banach Spaces [in Russian], Nauka, Moscow (1971).
2. Yu. K. Lando, “On the index and normal solvability of integrodifferential operators,” Differents. Uravn., 4, No. 6, 1112–1126 (1968).
3. V. F. Zhuravlev, "Bifurcation conditions for the solutions of weakly perturbed boundary-value problems for operator equations in Banach spaces," Ukr. Mat. Zh., 70, No. 3, 366-378 (2018)
4. English translation: Ukr. Math. J., 70, No. 3, 422-436 (2018).
5. V. P. Zhuravlev and M. P. Fomin, "Weakly perturbed integrodifferential equations with degenerate kernel in Banach spaces," Nelin. Kolyv., 23, No. 1, 184-199 (2020)