1. Hale J K, Kato J. Phase space for retarded equations with infinite delay. Funkcial Ekvac, 1978, 21: 11–41
2. Hino Y, Murakami S, Naito T. Functional-differential equations with infinite delay. In: Lecture Notes in Mathematics. Berlin: Springer-Verlag, 1991. 1473
3. Dauer J P, Mahmudov N I. Controllability of some nonlinear systems in Hilbert spaces. J Math Anal Appl, 2004, 123: 319–329
4. Fabre C, Puel J P, Zuazua E. Approximate controllability of semilinear heat equation. Proc Roy Soc Edinburgh Sect A, 1995, 125: 31–61
5. Fernandez L A, Zuazua E. Approximate controllability for semilinear heat equation involving gradient terms. J Optim Theory Appl, 1999, 101: 307–328