@article{DAN_1991_317_2_a18,
     author = {S. M. Zerkal'},
     title = {Determination of non-transparent regions in the {Earth} by method of computer
},
     journal = {Doklady Akademii Nauk},
     pages = {330--333},
     publisher = {mathdoc},
     volume = {317},
     number = {2},
     year = {1991},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1991_317_2_a18/}
}