@article{DE_1981_17_5_a9,
     author = {N. P. Erugin and M. M. Smirnov},
     title = {Functionally invariant solutions of differential equations},
     journal = {Differencialʹnye uravneni\^a},
     pages = {853--865},
     publisher = {mathdoc},
     volume = {17},
     number = {5},
     year = {1981},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1981_17_5_a9/}
}