@article{DAN_1962_146_2_a9,
     author = {N. V. Efimov},
     title = {Impossibility of an isometric imbedding in {Euclidean} 3-space of certain manifolds with negative {Gaussian} curvature},
     journal = {Doklady Akademii Nauk},
     pages = {296--299},
     publisher = {mathdoc},
     volume = {146},
     number = {2},
     year = {1962},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1962_146_2_a9/}
}