@article{GDZPPN002352311, title = {A Theorem of Beurling-Helson Type.}, journal = {Mathematica Scandinavica}, volume = {32}, year = {1973}, pages = {139-144}, zbl = {0271.43008}, url = {http://dml.mathdoc.fr/item/GDZPPN002352311} }
Domar, Yngve. A Theorem of Beurling-Helson Type.. Mathematica Scandinavica, Tome 32 (1973) pp. 139-144. http://gdmltest.u-ga.fr/item/GDZPPN002352311/