@article{GDZPPN002470071, title = {Symmetric Linear Operators on a Banach Space.}, journal = {Monatshefte f\"ur Mathematik}, volume = {53}, year = {1949}, pages = {278-297}, zbl = {0035.35901}, url = {http://dml.mathdoc.fr/item/GDZPPN002470071} }
Atkinson, F.V. Symmetric Linear Operators on a Banach Space.. Monatshefte für Mathematik, Tome 53 (1949) pp. 278-297. http://gdmltest.u-ga.fr/item/GDZPPN002470071/