Voir la notice de l'article provenant de la source Math-Net.Ru
@article{DAN_1990_314_5_a11, author = {A. H. Hovhannisyan}, title = {Structure of hyperbolic equations with variable coefficients that}, journal = {Doklady Akademii Nauk}, pages = {1072--1075}, publisher = {mathdoc}, volume = {314}, number = {5}, year = {1990}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DAN_1990_314_5_a11/} }
A. H. Hovhannisyan. Structure of hyperbolic equations with variable coefficients that. Doklady Akademii Nauk, Tome 314 (1990) no. 5, pp. 1072-1075. http://geodesic.mathdoc.fr/item/DAN_1990_314_5_a11/