@article{DAN_1961_139_5_a2,
     author = {R. M. Geidel'man},
     title = {The theory of a hypersurface in four-dimensional {non-Euclidean} spaces},
     journal = {Doklady Akademii Nauk},
     pages = {1040--1043},
     publisher = {mathdoc},
     volume = {139},
     number = {5},
     year = {1961},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1961_139_5_a2/}
}