@article{GDZPPN002283506, title = {On Some Approximate Methods Concerning the Operators T* T .}, journal = {Mathematische Annalen}, volume = {126}, year = {1953}, pages = {253-262}, zbl = {0051.09203}, url = {http://dml.mathdoc.fr/item/GDZPPN002283506} }
Kato, T. On Some Approximate Methods Concerning the Operators T* T .. Mathematische Annalen, Tome 126 (1953) pp. 253-262. http://gdmltest.u-ga.fr/item/GDZPPN002283506/