Voir la notice de l'article provenant de la source eLibrary of Mathematical Institute of the Serbian Academy of Sciences and Arts
@article{PIM_1982_N_S_32_46_a4, author = {Richard Bieberich}, title = {On {The} {Frequency} {With} {Which} {Bounded} {Functions} {Have} {Spectral} {Gaps}}, journal = {Publications de l'Institut Math\'ematique}, pages = {27 }, publisher = {mathdoc}, volume = {_N_S_32}, number = {46}, year = {1982}, url = {http://geodesic.mathdoc.fr/item/PIM_1982_N_S_32_46_a4/} }
Richard Bieberich. On The Frequency With Which Bounded Functions Have Spectral Gaps. Publications de l'Institut Mathématique, _N_S_32 (1982) no. 46, p. 27 . http://geodesic.mathdoc.fr/item/PIM_1982_N_S_32_46_a4/