@article{1008719034, author = {Duggal, B. P.}, title = {The operator inequality $P\sp {2k}\leq A\sp *P\sp {2k}A$}, journal = {Michigan Math. J.}, volume = {49}, number = {1}, year = {2001}, pages = { 39-45}, language = {en}, url = {http://dml.mathdoc.fr/item/1008719034} }
Duggal, B. P. The operator inequality $P\sp {2k}\leq A\sp *P\sp {2k}A$. Michigan Math. J., Tome 49 (2001) no. 1, pp. 39-45. http://gdmltest.u-ga.fr/item/1008719034/