@article{MS2_1993__73_2_167252,
     author = {Lars Ernstr\"om},
     title = {The spectrum associated to a radical operation.},
     journal = {Mathematica Scandinavica},
     pages = {5--14},
     publisher = {mathdoc},
     volume = {73},
     number = {2},
     year = {1993},
     zbl = {0790.14001},
     url = {http://geodesic.mathdoc.fr/item/MS2_1993__73_2_167252/}
}