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@article{DE_1975_11_1_a13, author = {N. I. Popivanov}, title = {Boundary value problems for degenerate multidimensional hyperbolic equations}, journal = {Differencialʹnye uravneni\^a}, pages = {116--126}, publisher = {mathdoc}, volume = {11}, number = {1}, year = {1975}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1975_11_1_a13/} }
N. I. Popivanov. Boundary value problems for degenerate multidimensional hyperbolic equations. Differencialʹnye uravneniâ, Tome 11 (1975) no. 1, pp. 116-126. http://geodesic.mathdoc.fr/item/DE_1975_11_1_a13/