Voir la notice de l'article provenant de la source Math-Net.Ru
@article{DE_2002_38_3_a17, author = {V. E. Balabaev}, title = {The {Ellipticity} {Problem} for {Systems} of {First-Order} {Partial} {Differential} {Equations}}, journal = {Differencialʹnye uravneni\^a}, pages = {411--413}, publisher = {mathdoc}, volume = {38}, number = {3}, year = {2002}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_2002_38_3_a17/} }
V. E. Balabaev. The Ellipticity Problem for Systems of First-Order Partial Differential Equations. Differencialʹnye uravneniâ, Tome 38 (2002) no. 3, pp. 411-413. http://geodesic.mathdoc.fr/item/DE_2002_38_3_a17/