Voir la notice de l'article provenant de la source Math-Net.Ru
@article{DE_1979_15_6_a11, author = {G. G. Kazaryan}, title = {Hyperbolic operators with a given higher-order part}, journal = {Differencialʹnye uravneni\^a}, pages = {1059--1069}, publisher = {mathdoc}, volume = {15}, number = {6}, year = {1979}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1979_15_6_a11/} }
G. G. Kazaryan. Hyperbolic operators with a given higher-order part. Differencialʹnye uravneniâ, Tome 15 (1979) no. 6, pp. 1059-1069. http://geodesic.mathdoc.fr/item/DE_1979_15_6_a11/