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@article{DE_1990_26_3_a16, author = {K. B. Sabitov}, title = {The maximum principle for systems of second-order equations of mixed type}, journal = {Differencialʹnye uravneni\^a}, pages = {488--494}, publisher = {mathdoc}, volume = {26}, number = {3}, year = {1990}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1990_26_3_a16/} }
K. B. Sabitov. The maximum principle for systems of second-order equations of mixed type. Differencialʹnye uravneniâ, Tome 26 (1990) no. 3, pp. 488-494. http://geodesic.mathdoc.fr/item/DE_1990_26_3_a16/