@article{DAN_1974_215_6_a8,
     author = {L. B. Sofman},
     title = {A problem of {Shannon}},
     journal = {Doklady Akademii Nauk},
     pages = {1313--1316},
     publisher = {mathdoc},
     volume = {215},
     number = {6},
     year = {1974},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1974_215_6_a8/}
}