@article{DAN_1972_207_5_a13,
     author = {F. V. Shirokov and V. A. Signayevskiy},
     title = {Minimum coverings of a finite set},
     journal = {Doklady Akademii Nauk},
     pages = {1066--1069},
     publisher = {mathdoc},
     volume = {207},
     number = {5},
     year = {1972},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1972_207_5_a13/}
}