@article{RM_2001_56_1_a1,
     author = {A. V. Zhiber and V. V. Sokolov},
     title = {Exactly integrable hyperbolic equations of {Liouville} type},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {61--101},
     publisher = {mathdoc},
     volume = {56},
     number = {1},
     year = {2001},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RM_2001_56_1_a1/}
}