@article{SIGMA_2012_8_a89,
     author = {Mariya N. Kuznetsova and Asli Pekcan and Anatoliy V. Zhiber},
     title = {The {Klein{\textendash}Gordon} {Equation} and {Differential} {Substitutions} of the {Form} $v=\varphi(u,u_x,u_y)$},
     journal = {Symmetry, integrability and geometry: methods and applications},
     year = {2012},
     volume = {8},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SIGMA_2012_8_a89/}
}