@article{IVM_1965_4_a13,
     author = {Ya. P. Ponarin},
     title = {Hyperbolic sines of tetrahedra and pentahedra in {Lobachevskii} space},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {113--121},
     publisher = {mathdoc},
     number = {4},
     year = {1965},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1965_4_a13/}
}