@article{DAN_1971_197_5_a0,
     author = {A. D. Aleksandrov},
     title = {Mapping families of cones},
     journal = {Doklady Akademii Nauk},
     pages = {991--994},
     publisher = {mathdoc},
     volume = {197},
     number = {5},
     year = {1971},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1971_197_5_a0/}
}