@article{GDZPPN001165615,
title = {An Elementary Proof of the Hopf Inequality for Positive Operators.},
journal = {Numerische Mathematik},
volume = {7},
year = {1965},
pages = {331-337},
zbl = {0148.38103},
url = {http://dml.mathdoc.fr/item/GDZPPN001165615}
}
BAUER, F.L. An Elementary Proof of the Hopf Inequality for Positive Operators.. Numerische Mathematik, Tome 7 (1965) pp. 331-337. http://gdmltest.u-ga.fr/item/GDZPPN001165615/