E. Albrecht, Decomposable systems of operators in harmonic analysis, in: Toeplitz Centennial, 19--35, (I. Gohberg, ed.), Birkhauser, Basel, 1983.
C. Apostol, Decomposable multiplication operators, Rev. Roumaine Math. Pures Appl. 17 (1972) 323--333.
A. G. Baskakov, Spectral synthesis in Banach modules over commutative Banach algebras, Math. Notes 34 (1983), no. 4, 776--782.
J. Bračič, Unital strongly harmonic commutative Banach algebras, Studia Math. 149 (2002), 253--266.
J. Bračič, Strongly harmonic operators, Acta Sci. Math. (Szeged) 68 (2002), 797--813.
I. Colojoara and C. Foias, Theory of Generalized Spectral Operators, Gordon and Breach, New York, 1968.
St. Frunza, A characterization of regular Banach algebras, Rev. Roumaine Math. Pures Appl. 18 (1973), 1057--1059.
J. Inoue and S.-E. Takahasi, A note on the largest regular subalgebra of a Banach algebra, Proc. Amer. Math. Soc. 116 (1992) 961--962.
E. Kaniuth, A Course in Commutative Banach Algebras, Graduate Texts in Mathematics 246, Springer, New York, 2009.
K. B. Laursen and M. M. Neumann, An Introduction to Local Spectral Theory, London Math. Soc. Monographs 20, Clarendon Press, Oxford, 2000.
M. M. Neumann, Commutative Banach algebras and decomposable operators, Monatsh. Math. 113 (1992), 227--243.
M. M. Neumann,Banach algebras, decomposable convolution operators, and a spectral mapping property, in: Function spaces, (K. Jarosz, ed.), Marcel Dekker, New York (1992), 307--323.
C. E. Rickart, General Theory of Banach Algebras, Van Nostrand, Princeton 1960.