@article{UZMU_1951_148_148_a13,
     author = {Yu. M. Smirnov},
     title = {On coverings of topological spaces},
     journal = {Uchenye Zapiski Moskovskogo Gosudarstvennogo Universiteta},
     pages = {204--215},
     year = {1951},
     volume = {148},
     number = {148},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/UZMU_1951_148_148_a13/}
}