%0 Journal Article %A Putnam, C.R. %T Commutators and normal operators %J Portugaliae mathematica %D 1958 %P 59-62 %V 17 %N 2 %I mathdoc %U http://geodesic.mathdoc.fr/item/PORMA_1958__17_2_114801/ %G en %F PORMA_1958__17_2_114801