@article{IVM_1988_12_a6,
     author = {G. O. \`El'sting},
     title = {On the connection between {Cartan} prolongations of depth~2 and depth~1},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {49--50},
     publisher = {mathdoc},
     number = {12},
     year = {1988},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1988_12_a6/}
}