@article{JRAM_1980__317_152260,
     author = {Dieter Leitmann},
     title = {Absch\"atzung trigonometrischer {Summen.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {209--219},
     publisher = {mathdoc},
     volume = {317},
     year = {1980},
     zbl = {0421.10024},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1980__317_152260/}
}