@article{DAN_1958_118_3_a5,
     author = {L. V. Ovsyannikov},
     title = {Groups and invariant-group solutions of differential equations},
     journal = {Doklady Akademii Nauk},
     pages = {439--442},
     publisher = {mathdoc},
     volume = {118},
     number = {3},
     year = {1958},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1958_118_3_a5/}
}