@article{DAN_1962_143_4_a20,
     author = {V. M. Fridkin},
     title = {Iso-opaque in electro-photography},
     journal = {Doklady Akademii Nauk},
     pages = {825--828},
     publisher = {mathdoc},
     volume = {143},
     number = {4},
     year = {1962},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1962_143_4_a20/}
}