1. Linear Operators I, II;Dunford,1964
2. Stability of solutions to linear operator equations of the first kind and second kinds under perturbation of the operator with rank change;Engl,1980
3. On the Convergence of Regularization Methods for Ill-Posed Linear Operator Equations;Engl,1983
4. The Theory of Tikhonov Regularization for Fredholm Equations of the First Kind;Groetsch,1984
5. C. W. Groetsch, private communication, unpublished, 1983.