@article{AFM_1963_316-335_a6,
     author = {Toivo Nieminen},
     title = {On the norm of a linear operator in a {Hilbert} space},
     journal = {Annales Fennici Mathematici},
     publisher = {mathdoc},
     volume = {316-335},
     year = {1963},
     doi = {10.5186/aasfm.1963.329},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.5186/aasfm.1963.329/}
}