@article{NGWGMP_1930__1930_59324,
     author = {Z. W. Birnbaum},
     title = {Zur {Approximation} im {Mittel}},
     journal = {Nachrichten von der Gesellschaft der Wissenschaften zu G\"ottingen, Mathematisch-Physikalische Klasse},
     pages = {338--343},
     publisher = {mathdoc},
     volume = {1930},
     year = {1930},
     zbl = {56.0931.02},
     url = {http://geodesic.mathdoc.fr/item/NGWGMP_1930__1930_59324/}
}