@article{01413878, title = {Contact geometry of hyperbolic Monge-Amp\'ere equations.}, journal = {Lobachevskii Journal of Mathematics}, volume = {3}, year = {1999}, pages = {109-162}, zbl = {0938.35011}, language = {en}, url = {http://dml.mathdoc.fr/item/01413878} }
Tchij, O.P. Contact geometry of hyperbolic Monge-Ampére equations.. Lobachevskii Journal of Mathematics, Tome 3 (1999) pp. 109-162. http://gdmltest.u-ga.fr/item/01413878/