@article{MZ_1928__28_168022,
     author = {J. G., van der Corput},
     title = {Beweis einer approximativen {Funktionalgleichung}},
     journal = {Mathematische Zeitschrift},
     pages = {238--300},
     year = {1928},
     volume = {28},
     zbl = {54.0205.01},
     url = {http://geodesic.mathdoc.fr/item/MZ_1928__28_168022/}
}