@article{SM_1997_188_5_a6,
     author = {D. V. Tunitsky},
     title = {Equivalence and characteristic connections of {the~Monge{\textendash}Ampere} equations},
     journal = {Sbornik. Mathematics},
     pages = {771--797},
     year = {1997},
     volume = {188},
     number = {5},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1997_188_5_a6/}
}