@article{MAT_1957_1_2_a1,
     author = {N. H. Kuiper},
     title = {On $C^1$-isometric {imbeddings.~I}},
     journal = {Matematika},
     pages = {17--28},
     publisher = {mathdoc},
     volume = {1},
     number = {2},
     year = {1957},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MAT_1957_1_2_a1/}
}