@article{DE_1993_29_10_a12,
     author = {S. R. Svirshchevskii},
     title = {Group classification and invariant solutions of nonlinear polyharmonic equations},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1772--1781},
     publisher = {mathdoc},
     volume = {29},
     number = {10},
     year = {1993},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1993_29_10_a12/}
}