1. The Fredholm elements of a ring;B.A. Barnes;Canadian Journal of Mathematics,1969
2. B.A. Barnes, G.J. Murphy, M.R.F. Smyth and T.T. West, Riesz and Fredholm theory in Banach algebras, Research Notes in Mathematics no. 67, Pitman, London, 1982.
3. On one-sided primitivity of Banach algebras;M.J. Crabb;Proceedings of the Edinburgh Mathematical Society,2010
4. N. Jacobson, Structure of rings, American Mathematical Society Colloquium Publications no. 37, American Mathematical Society, Providence, Rhode Island, 1964.
5. The spectral radius formula in quotient algebras;M.R.F. Smyth;Mathematische Zeitschrift,1975