@article{MZM_1973_13_5_a6,
     author = {A. K. Guts},
     title = {Mappings that preserve cones in {Lobachevskii} space},
     journal = {Matemati\v{c}eskie zametki},
     pages = {687--694},
     publisher = {mathdoc},
     volume = {13},
     number = {5},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1973_13_5_a6/}
}