@article{MAN_1921__83_158859,
     author = {O. Perron},
     title = {\"Uber diophantische {Approximationen}},
     journal = {Mathematische Annalen},
     pages = {77--84},
     publisher = {mathdoc},
     volume = {83},
     year = {1921},
     zbl = {48.0194.01},
     url = {http://geodesic.mathdoc.fr/item/MAN_1921__83_158859/}
}