@article{GDZPPN002304597, title = {Roots of Unity and Covering Sets.}, journal = {Mathematische Annalen}, volume = {193}, year = {1971}, pages = {279-282}, zbl = {0203.35205}, url = {http://dml.mathdoc.fr/item/GDZPPN002304597} }
NEWMAN, M. Roots of Unity and Covering Sets.. Mathematische Annalen, Tome 193 (1971) pp. 279-282. http://gdmltest.u-ga.fr/item/GDZPPN002304597/