@article{ZNSL_1977_67_a1,
     author = {D. S. Gorshkov},
     title = {Geometry of {Lobachevskii} in connection with certain questions of arithmetic},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {39--85},
     publisher = {mathdoc},
     volume = {67},
     year = {1977},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1977_67_a1/}
}