@article{05228042, title = {Elementary formulas for a hyperbolic tetrahedron.}, journal = {Sibirskij Matematicheskij Zhurnal}, volume = {47}, year = {2006}, pages = {831-841}, zbl = {1150.51305}, language = {en}, url = {http://dml.mathdoc.fr/item/05228042} }
Mednykh, A.D.; Pashkevich, M.G. Elementary formulas for a hyperbolic tetrahedron.. Sibirskij Matematicheskij Zhurnal, Tome 47 (2006) pp. 831-841. http://gdmltest.u-ga.fr/item/05228042/