1. A continuous selection of the metric projection in matrix spaces;Berens,1987
2. Matrix Computations;Golub,1989
3. Symmetric gauge functions and unitarily invariant norms;Mirsky;Quart. J. Math. Oxford Ser. (2),1960
4. Some matrix inequalities and metrization of metric spaces;von Neumann;Tomsk Univ. Rev.,1937
5. Perturbation Theory of Eigenvalue Problems;Rellich,1969