@article{02112562, title = {Ivory's theorem in hyperbolic spaces.}, journal = {Sibirskij Matematicheskij Zhurnal}, volume = {45}, year = {2004}, pages = {946-959}, zbl = {1051.51012}, language = {en}, url = {http://dml.mathdoc.fr/item/02112562} }
Stachel, Hellmuth; Wallner, Johannes. Ivory's theorem in hyperbolic spaces.. Sibirskij Matematicheskij Zhurnal, Tome 45 (2004) pp. 946-959. http://gdmltest.u-ga.fr/item/02112562/