@article{MAN_1928__98_159206,
     author = {S. Borgen},
     title = {\"Uber {(C} 1) - {Summierbarkeit} von {Reihen} orthogonaler {Funktionen}},
     journal = {Mathematische Annalen},
     pages = {125--150},
     publisher = {mathdoc},
     volume = {98},
     year = {1928},
     zbl = {53.0267.02},
     url = {http://geodesic.mathdoc.fr/item/MAN_1928__98_159206/}
}