@article{DAN_1972_202_6_a7,
     author = {A. V. Ostrovsky},
     title = {On $k$-covering mappings of separable metric spaces},
     journal = {Doklady Akademii Nauk},
     pages = {1271--1273},
     publisher = {mathdoc},
     volume = {202},
     number = {6},
     year = {1972},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1972_202_6_a7/}
}