1. P. Acquistapace -B. Terreni,Some existence and regularity results for abstract nonautonomous parabolic equations, J. Math. Anal. Appl.,99 (1984), pp. 9–64.
2. S. Agmon,On the eigenfunctions and the eigenvalues of general elliptic boundary value problems, Comm. Pure Appl. Math.,15 (1962), pp. 119–147.
3. H. Amann,Periodic solutions of semi-linear parabolic equations, Nonlinear analysis, a collection of papers in honour of E. H. Rothe, ed. L. Cesari, R. Kannan, H. F. Weinberger, Academic Press, New York, 1978.
4. [4]J. B. Baillon,Caractére borné de certains générateurs de semi-groupes linéaires dans les espaces de Banach, C. R. Acad. Sci. Paris,290 (28 avril 1980), série A, pp. 757–760.
5. P. L. Butzer -H. Berens,Semi-groups of operators and approximation, Springer-Verlag, Berlin 1967.