@article{MZ_1922__12_167673,
     author = {H. Cram\'er},
     title = {Ein {Mittelwertsatz} in der {Primzahltheorie}},
     journal = {Mathematische Zeitschrift},
     pages = {147--153},
     publisher = {mathdoc},
     volume = {12},
     year = {1922},
     zbl = {48.1178.03},
     url = {http://geodesic.mathdoc.fr/item/MZ_1922__12_167673/}
}