@article{DAN_1973_208_1_a5,
     author = {N. V. Efimov and Z. D. Usmanov},
     title = {Infinitesimal bending of a surface with a point of flatness},
     journal = {Doklady Akademii Nauk},
     pages = {28--31},
     publisher = {mathdoc},
     volume = {208},
     number = {1},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1973_208_1_a5/}
}