1. K. Y. Fan, Generalization of Bergsrröm inequality, American Mathematical Monthly, 66 (2) (1959), 153-154.;
2. H. Bergström, A triangle inequality for matrices, Den Elfte Skandinaviske Matematikerkongress, Trondheim, 1949, Johan Grundt Tanums Forlag, Oslo, 1952, 264-267.;
3. R. Bellman, Notes on matrix theory-IV (An inequality due to Bergström), American Mathematical Monthly, 62 (3) (1955), 172-173.;
4. S. Abramovich, B. Mond, J. E. Pecaric, Sharpening Jensen’s inequality and a majorization theorem, Journal of Mathematical Analysis and Applications, 214 (2) (1997), 721-728.;
5. J. E. Pecaric, F. Proschan, Y. I. Tong, Convex Functions, Partial Orderings, and Statistical Applications, Mathematics in Science and Engineering, Academic Press, San Diego, CA, 1992.;