@article{KUTGS_1986_17_a2,
     author = {V. G. Kopp},
     title = {Invariants of groups of infinitesimal motions of a three-dimensional {Lorentz} space},
     journal = {Trudy Geometricheskogo Seminara},
     pages = {13--29},
     publisher = {mathdoc},
     volume = {17},
     year = {1986},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/KUTGS_1986_17_a2/}
}