@article{DAN_1983_272_1_a7,
     author = {V. V. Lychagin and V. N. Rubtsov},
     title = {Local classification of {Monge{\textendash}Amp\`ere} differential equations},
     journal = {Doklady Akademii Nauk},
     pages = {34--38},
     year = {1983},
     volume = {272},
     number = {1},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1983_272_1_a7/}
}