1. Maximum properties and inequalities for the eigenvalues of completely continuous operators;Fan, Ky;Proc. Nat. Acad. Sci. U.S.A.,1951
2. On the characteristic numbers of the sum and product of symmetric matrices;Lidskiĭ, V. B.;Doklady Akad. Nauk SSSR (N.S.),1950
3. J. von Neumann, Some matrix-inequalities and metrization of matric-space, Tomsk Univ. Rev. vol. 1 (1937) pp. 286-300.
4. Annals of Mathematics Studies, No. 26;Schatten, Robert,1950
5. An extremum property of sums of eigenvalues;Wielandt, Helmut;Proc. Amer. Math. Soc.,1955