@article{MZ_1991__206_1_174217,
     author = {Ruth Kellerhals},
     title = {On {Schl\"afli's} reduction formula.},
     journal = {Mathematische Zeitschrift},
     pages = {193--210},
     publisher = {mathdoc},
     volume = {206},
     number = {1},
     year = {1991},
     zbl = {0717.52011},
     url = {http://geodesic.mathdoc.fr/item/MZ_1991__206_1_174217/}
}