1. On distances between unitary orbits of self-adjoint operators;Azoff;Acta Sci. Math. (Szeged),1984
2. R. Bhatia, “Perturbation Bounds for Matrix Eigenvalues, Lecture Notes 1986,” to appear in the Pitman Research Notes series.
3. Perturbation of spectral subspaces and solution of linear operator equations;Bhatia;Linear Algebra Appl.,1983
4. The distance between unitary orbits of normal operators;Davidson;Acta Sci. Math. (Szeged),1986