@article{DAN_1974_218_3_a1,
     author = {V. Ya. Gutlyanskii and V. A. Shchepetev},
     title = {A generalized area theorem for a class of $q$-quasi-conformal mappings},
     journal = {Doklady Akademii Nauk},
     pages = {509--512},
     publisher = {mathdoc},
     volume = {218},
     number = {3},
     year = {1974},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1974_218_3_a1/}
}