@article{DAN_1973_211_6_a0,
     author = {A. D. Aleksandrov},
     title = {Mappings that preserve congruence},
     journal = {Doklady Akademii Nauk},
     pages = {1257--1260},
     publisher = {mathdoc},
     volume = {211},
     number = {6},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1973_211_6_a0/}
}