@article{MAN_1943__119_160129,
     author = {O. Perron},
     title = {Neuer {Aufbau} der nichteuklidischen (hyperbolischen) {Trigonometrie}},
     journal = {Mathematische Annalen},
     pages = {247--265},
     publisher = {mathdoc},
     volume = {119},
     year = {1943},
     zbl = {0060.33008},
     url = {http://geodesic.mathdoc.fr/item/MAN_1943__119_160129/}
}