@article{MS2_1973__33_166320,
     author = {Yngve Domar},
     title = {A {Theorem} of {Beurling-Helson} {Type.}},
     journal = {Mathematica Scandinavica},
     pages = {139--144},
     publisher = {mathdoc},
     volume = {33},
     year = {1973},
     zbl = {0271.43008},
     url = {http://geodesic.mathdoc.fr/item/MS2_1973__33_166320/}
}