@article{MZ_1965__90_170474,
     author = {Oskar Perron},
     title = {\"Uber {\"Ahnlichkeit,} {Dehnung} und {Schrumpfung} in der hyperbolischen {Geometrie.}},
     journal = {Mathematische Zeitschrift},
     pages = {160--184},
     publisher = {mathdoc},
     volume = {90},
     year = {1965},
     zbl = {0133.13704},
     url = {http://geodesic.mathdoc.fr/item/MZ_1965__90_170474/}
}