@article{VMUMM_2015_5_a2,
     author = {K. A. Popkov},
     title = {Single tests for contacts},
     journal = {Vestnik Moskovskogo universiteta. Matematika, mehanika},
     pages = {13--18},
     year = {2015},
     number = {5},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMUMM_2015_5_a2/}
}