[AFHV] C. Apostol L. A. Fialkow D. A. Herrero D. Voiculescu: Approximation of Hilbert space operators. volume II, Research Notes in Mathematics 102 (Pitman, Boston, 1984). MR 0735080

[B1] L. Burlando: On two subsets of a Banach algebra that are related to the continuity of spectrum and spectral radius. Linear Algebra Appl., 84, (1986), 251 - 269. DOI 10.1016/0024-3795(86)90318-6 | MR 0872287 | Zbl 0612.46046

[B2] L. Burlando: Continuity of spectrum and spectral radius in algebras of operators. to appear. MR 0971812 | Zbl 0618.47003

[BHOP] C. Bosh C. Hernandez E. De Oteyza C. Pearcy: Spectral pictures of functions of operators. J. Operator Theory, 8 (1982), 391-400. MR 0677420

[CM] J. B. Conway B. B. Morrel: Operators that are points of spectral continuity, integral Equations and Operator Theory. 2 (1979), 174-198. DOI 10.1007/BF01682733 | MR 0543882

[CPY] S. R. Caradus W. E. Pfaffenberger B. Yood: Calkin algebras and algebras of operators on Banach spaces. Lecture Notes in Pure and Applied Mathematics 9 (Marcel Dekker, New York, 1974). MR 0415345

[GL] B. Gramsch D. Lay: Spectral mapping theorems for essential spectra. Math. Ann., 192 (1971), 17-32. DOI 10.1007/BF02052728 | MR 0291846

[H] P. R. Halmos: A Hilbert space problem book. (Van Nostrand, Princeton, 1967). MR 0208368 | Zbl 0144.38704

[K] T. Kato: Perturbation theory for linear operators. (Springer, New York, 1966). MR 0203473 | Zbl 0148.12601

[R] W. Rudin: Real and complex analysis. (McGraw-Hill, New York, 1966). MR 0210528 | Zbl 0142.01701

[TL] A. E. Taylor D. C. Lay: Introduction to functional analysis. second edition (John-WiIey & Sons, New York, 1980). MR 0564653