@article{MAN_1890__35_157474,
     author = {Illigens},
     title = {Zur {Definition} der {Irrationalzahlen}},
     journal = {Mathematische Annalen},
     pages = {451--455},
     year = {1890},
     volume = {35},
     url = {http://geodesic.mathdoc.fr/item/MAN_1890__35_157474/}
}