@article{10_1017_S0017089500004821,
     author = {Albrecht, Ernst},
     title = {A characterization of spectral operators on {Hilbert} spaces},
     journal = {Glasgow mathematical journal},
     pages = {91--95},
     year = {1982},
     volume = {23},
     number = {1},
     doi = {10.1017/S0017089500004821},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089500004821/}
}