@article{GDZPPN002318490, title = {An Operator Inequality.}, journal = {Mathematische Annalen}, volume = {243}, year = {1979}, pages = {249-250}, zbl = {0407.47012}, url = {http://dml.mathdoc.fr/item/GDZPPN002318490} }
Hansen, Frank. An Operator Inequality.. Mathematische Annalen, Tome 243 (1979) pp. 249-250. http://gdmltest.u-ga.fr/item/GDZPPN002318490/