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@article{DAN_1986_287_3_a8, author = {M. E. Lerner}, title = {Maximum principles for equations of hyperbolic and mixed types in}, journal = {Doklady Akademii Nauk}, pages = {550--554}, publisher = {mathdoc}, volume = {287}, number = {3}, year = {1986}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DAN_1986_287_3_a8/} }
M. E. Lerner. Maximum principles for equations of hyperbolic and mixed types in. Doklady Akademii Nauk, Tome 287 (1986) no. 3, pp. 550-554. http://geodesic.mathdoc.fr/item/DAN_1986_287_3_a8/