[1] Kato, T.: Perturbation theory for nullity, deficiency and other quantities of linear operators. J. Anal. Math., 6, 261-322 (1958)

[2] Mbekhta, M.: Généralisation de la décomposition de Kato aux opérateurs paranormaux et spectraux. Glasgow Math. J., 29, 159-17 (1987)

[3] Mbekhta, M.: Résolvant généralisé et théorie spectrale. J. Operator Theory, 21, 69-105 (1989)

[4] Mbekhta, M.: On the generalized resolvent in Banach spaces. J. Math. Anal. Appl., 189, 362-377 (1995)

[5] Mbekhta, M., Ouahab, A.: Opérateur s-régulier dans un espace de Banach et théorie spectrale. Acta Sci. Math. (Szeged), 59, 525-543 (1994)

[6] Schmoeger, C.: On isolated points of the spectrum of a bounded operator. Proc. Amer. Math. Soc., 117, 715-719 (1993)

[7] Cross, R. W.: Multivalued Linear Operators, Marcel Dekker, New York, 1998

[8] von Neumann, J.: Functional Operators, Vol. 2, The Geometry of Orthogonal Spaces, Ann. of Math. Stud., Princeton University Press, Princeton, 1950

[9] Coddington, E. A.: Multivalued operators and boundary value problems, Lecture Notes in Math. 183, Springer-Verlag, Berlin, 1971

[10] Favini, A., Yagi, A.: Multivalued linear operators and degenerate evolution equations. Ann. Mat. Pura Appl., 163(4), 353-384 (1993)

[11] Favini, A., Yagi, A.: Degenerate Differential Equations in Banach Spaces, Marcel Dekker, New York, 1998

[12] Gromov, M.: Partial Differential Relations, Springer-Verlag, Berlin, 1986

[13] Agarwal, R. P., Meehan, M., O'Regan, D.: Fixed Point Theory and Applications, Cambridge University Press, Cambridge, 2001

[14] Gorniewicz, L.: Topological fixed Point Theory of Multivalued Mappings, Kluwer, Dordrecht, 1999

[15] Grixti-Cheng, D.: The invariant subspace problem for linear relations on Hilbert spaces. J. Austr. Math. Anal. Appl., 5, 1-7 (2008)

[16] Saveliev, P.: Lomonosov's invariant subspace theorem for multivalued linear operators. Proc. Amer. Math. Soc., 131(3), 825-834 (2003)

[17] Baskakov, A. G., Chernyshov, K. I.: Spectral analysis of linear relations and degenerate operator semigroups. Sbornik Math., 193(11), 1573-1610 (2002)

[18] Alvarez, T., Cross, R. W., Wilcox, D.: Multivalued Fredholm type operators with abstract generalised inverses. J. Math. Anal. Appl., 261, 403-417 (2001)

[19] Alvarez, T., Cross, R. W., Wilcox, D.: Quantities related to upper and lower semiFredholm type linear relations. Bull. Austr. Math. Soc., 66, 275-289 (2002)

[20] Labrousse, J.-Ph., Sandovici, A., de Snoo, H. S. V., et al.: Quasi-Fredholm relations in Hilbert spaces. Stud. Cercet. Stiint. Ser. Mat. Univ. Bacau, 16, 93-105 (2006)

[21] Sandovici, A.: Some basic properties of polynomials in a linear relation in linear spaces. Oper. Theory Adv. Appl. 175, Birkh¨auser, Basel, 2007, 231-240

[22] Goldberg, S.: Unbounded Linear Operators. Theory and Aplications, McGraw-Hill, New York, 1966

[23] Sandovici, A., de Snoo, H. S. V., Winkler, H.: Ascent, descent, nullity, defect, and related notions for linear relations in linear spaces. Linear Algebra and its Applications, 423, 456-497 (2007)

[24] Müller, V.: On the regular spectrum. J. Operator Theory, 31, 363-380 (1994)

[25] West, T. T.: Removing the jump-Kato's decomposition. Rocky Mount. J. Math., 20, 603-612 (1990)