@article{GDZPPN002283298,
title = {Perturbation Theory of Semi-Bounded Operators.},
journal = {Mathematische Annalen},
volume = {125},
year = {1952},
pages = {435-447},
zbl = {0050.34502},
url = {http://dml.mathdoc.fr/item/GDZPPN002283298}
}
Kato, T. Perturbation Theory of Semi-Bounded Operators.. Mathematische Annalen, Tome 125 (1952) pp. 435-447. http://gdmltest.u-ga.fr/item/GDZPPN002283298/