@article{IM2_1984_22_2_a4,
     author = {Yu. B. Orochko},
     title = {Finite local propagation rate of a~hyperbolic equation in the problem of selfadjointness of powers of a~second order elliptic differential operator},
     journal = {Izvestiya. Mathematics},
     pages = {277--290},
     year = {1984},
     volume = {22},
     number = {2},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1984_22_2_a4/}
}