@article{TMF_1992_92_1_a0,
     author = {A. V. Shapovalov and I. V. Shirokov},
     title = {Symmetry algebras of linear differential equations},
     journal = {Teoreti\v{c}eska\^a i matemati\v{c}eska\^a fizika},
     pages = {3--12},
     publisher = {mathdoc},
     volume = {92},
     number = {1},
     year = {1992},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TMF_1992_92_1_a0/}
}