@article{MZM_2023_114_1_a13,
     author = {Yu. L. Sachkov},
     title = {Lorentzian {Geometry} on the {Lobachevsky} {Plane}},
     journal = {Matemati\v{c}eskie zametki},
     pages = {154--157},
     year = {2023},
     volume = {114},
     number = {1},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_2023_114_1_a13/}
}