@article{PORMA_1958__17_2_114801,
     author = {Putnam, C.R.},
     title = {Commutators and normal operators},
     journal = {Portugaliae mathematica},
     pages = {59--62},
     publisher = {mathdoc},
     volume = {17},
     number = {2},
     year = {1958},
     mrnumber = {0098989},
     zbl = {0151.20102},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PORMA_1958__17_2_114801/}
}