@article{DE_2002_38_10_a13,
     author = {D. P. Kostomarov},
     title = {An {Application} of the {Averaging} {Method} and {Hadamard's} {Method} of {Descent} to the {Analysis} of the {Cauchy} {Problem} for an {Ultra-Hyperbolic} {Equation}},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1397--1403},
     publisher = {mathdoc},
     volume = {38},
     number = {10},
     year = {2002},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_2002_38_10_a13/}
}