@article{MAN_1930__103_159436,
     author = {O. Perron},
     title = {\"Uber die {Approximation} einer komplexen {Zahl} durch {Zahlen} des {K\"orpers} .... (i)},
     journal = {Mathematische Annalen},
     pages = {533--544},
     publisher = {mathdoc},
     volume = {103},
     year = {1930},
     zbl = {56.0896.02},
     url = {http://geodesic.mathdoc.fr/item/MAN_1930__103_159436/}
}