[[1] W. Arendt, C. J. K. Batty, M. Hieber, and F. Neubrander, Vector-valued Laplace Transforms and Cauchy Problems, Monographs in Mathematics, 96, Birkh¨auser-Springer, Basel, 2011.10.1007/978-3-0348-0087-7]Search in Google Scholar
[[2] H. O. Fattorini, Ordinary differential equations in linear topological space, II, J. Differential Equations 6 (1969), 50-70.10.1016/0022-0396(69)90117-X]Search in Google Scholar
[[3] J.P. Labrousse, Inverses généralisés d’opérateurs non-bornés, Proc. Amer. Math. Soc. 115(1992), 125-129.10.1090/S0002-9939-1992-1079701-6]Search in Google Scholar
[[4] J.P. Labrousse, Les opérateurs quasi-Fredholm: une généralisation des opérateurs semi-Fredholm, Rend. Circ. Math. Palermo (2), XXIX (1980) 161-258.10.1007/BF02849344]Search in Google Scholar
[[5] D. Lutz, Strongly continuous operator cosine functions, Functional Analysis (Dubrovnik, 1981). (Lecture Notes in Math., Vol. 948), Springer, Berlin-New York, 1982, 73-97.10.1007/BFb0069842]Search in Google Scholar
[[6] M. Mbekhta, A. Ouahab, Opérateur s-régulier dans un espace de Banach et théorie spectrale, Acta Sci. Math. (Szeged) 59 (1994), 525-543.]Search in Google Scholar
[[7] V. Müller, Spectral Theory of Linear Operators and Spectral Systems in Banach Algebras, 2nd edition. Oper. Theory Advances and Applications, vol. 139 (2007).]Search in Google Scholar
[[8] B. Nagy, On cosine operator functions on Banach spaces, Acta Sci. Math. Szeged 36 (1974), 281-290.]Search in Google Scholar
[[9] A. Tajmouati, M. Amouchb, M. KarmouniaSymmetric Difference Between Pseudo B-Fredholm Spectrum and Spectra Originated from Fredholm Theory, Filomat 31(16)(2017), 5057-5064.10.2298/FIL1716057T]Search in Google Scholar
[[10] C. C. Travis and G. F. Webb, Cosine families and abstract nonlinear second order differential equations, Acta Math. Acad. Sci. Hungar. 32 (1978),75-96.10.1007/BF01902205]Search in Google Scholar
[[11] H. O. Fattorini, Uniformly bounded cosine functions in Hilbert spaces, Indiana Univ. Math. J. 20 (1970), 411-425.10.1512/iumj.1971.20.20035]Search in Google Scholar
[[12] S. Kurepa, cosine functkmal equation in Hilbert space, Canad. J. Math., 12 (1960), 45-49.10.4153/CJM-1960-005-7]Search in Google Scholar