@article{MZ_1933__37_168431,
     author = {E. Landau},
     title = {\"Uber eine trigonometrische {Ungleichung.}},
     journal = {Mathematische Zeitschrift},
     pages = {36--36},
     year = {1933},
     volume = {37},
     language = {de},
     url = {http://geodesic.mathdoc.fr/item/MZ_1933__37_168431/}
}