@article{VMUMM_1995_1_a14,
     author = {N. A. Bokaev},
     title = {On $U$-sets for multiplicative systems},
     journal = {Vestnik Moskovskogo universiteta. Matematika, mehanika},
     pages = {84--86},
     year = {1995},
     number = {1},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMUMM_1995_1_a14/}
}