@article{MMO_1975_33_a5,
     author = {M. A. \v{S}ifrin},
     title = {Theorems of {Liouville} type for higher order elliptic equations},
     journal = {Trudy Moskovskogo matemati\v{c}eskogo ob\^{s}estva},
     pages = {263--278},
     publisher = {mathdoc},
     volume = {33},
     year = {1975},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MMO_1975_33_a5/}
}