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@article{DE_1973_9_1_a17, author = {N. G. Sorokina}, title = {Energy relations for multidimensional equations of mixed type}, journal = {Differencialʹnye uravneni\^a}, pages = {158--161}, publisher = {mathdoc}, volume = {9}, number = {1}, year = {1973}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1973_9_1_a17/} }
N. G. Sorokina. Energy relations for multidimensional equations of mixed type. Differencialʹnye uravneniâ, Tome 9 (1973) no. 1, pp. 158-161. http://geodesic.mathdoc.fr/item/DE_1973_9_1_a17/