@article{MAN_1984__268_182908,
     author = {Edwin Hewitt and Gavin Brown},
     title = {A {Class} of {Positive} {Trigonometrie} {Sums.}},
     journal = {Mathematische Annalen},
     pages = {91--122},
     year = {1984},
     volume = {268},
     zbl = {0522.42001},
     url = {http://geodesic.mathdoc.fr/item/MAN_1984__268_182908/}
}