1. H. Bounit and A. Fadili. On the Favard spaces and the admissibility for Volterra systems with scalar kernel. Electronic Journal of Differential Equations, (2015):N 42 pp. 1–21, 2015.
2. P.L. Butzer and H. Berens. Semi-Groups of Operators and Approximation. Springer-Verlag, New York, 1967.
3. Counterexamples for Abstract Linear Volterra Equations
4. W. Desch and W. Schappacher. Some generation results for perturbed semigroups, in semigroups theory and applications, (Procedings Trieste 1987) (P. Clément, S. Invernizzi, E. Mitidieri and I.I. Vrabie, eds). Marcel Dekker, Lec. notes in pure and Appl, 116:125–152, 1989.
5. K. J. Engel and R. Nagel. One-parameter semigroups for linear evolution equations. New York, Berlin, Heidelberg, 2000.