@article{MZ_1930__31_168166,
     author = {Oskar Perron},
     title = {\"Uber eine {Formel} des {Herrn} {Schwatt}},
     journal = {Mathematische Zeitschrift},
     pages = {159--160},
     publisher = {mathdoc},
     volume = {31},
     year = {1930},
     zbl = {55.0132.09},
     url = {http://geodesic.mathdoc.fr/item/MZ_1930__31_168166/}
}