@article{DAN_1981_257_4_a0,
     author = {P. A. Biryukov},
     title = {Ranks of families of sets and properties of topological spaces},
     journal = {Doklady Akademii Nauk},
     pages = {777--779},
     year = {1981},
     volume = {257},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1981_257_4_a0/}
}