@article{JRAM_1961__207_150482,
     author = {Gilbert Helmberg},
     title = {Zerlegungen des {Mittelwertes} fastperiodischer {Funktionen.} {I.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {31--52},
     publisher = {mathdoc},
     volume = {207},
     year = {1961},
     zbl = {0105.31302},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1961__207_150482/}
}