@article{VMUMM_1985_2_a0,
     author = {I. V. Chernykh},
     title = {Some properties of clustering operators},
     journal = {Vestnik Moskovskogo universiteta. Matematika, mehanika},
     pages = {3--6},
     publisher = {mathdoc},
     number = {2},
     year = {1985},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMUMM_1985_2_a0/}
}