@article{DM_1993_5_1_a1,
     author = {V. N. Sachkov},
     title = {Asymptotics of the number of $t$-minimal coverings of a~set},
     journal = {Diskretnaya Matematika},
     pages = {36--44},
     year = {1993},
     volume = {5},
     number = {1},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DM_1993_5_1_a1/}
}