@article{DAN_1966_168_3_a1,
     author = {B. D. Annin},
     title = {A certain property of a solution of the equation $u_{xx}u_{yy}-u_{xy}^2=1$},
     journal = {Doklady Akademii Nauk},
     pages = {499--501},
     publisher = {mathdoc},
     volume = {168},
     number = {3},
     year = {1966},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1966_168_3_a1/}
}