Voir la notice de l'article provenant de la source Math-Net.Ru
@article{DAN_1978_238_2_a2, author = {V. V. Lychagin}, title = {Nonlinear differential equations and contact geometry}, journal = {Doklady Akademii Nauk}, pages = {273--276}, publisher = {mathdoc}, volume = {238}, number = {2}, year = {1978}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DAN_1978_238_2_a2/} }
V. V. Lychagin. Nonlinear differential equations and contact geometry. Doklady Akademii Nauk, Tome 238 (1978) no. 2, pp. 273-276. http://geodesic.mathdoc.fr/item/DAN_1978_238_2_a2/