@article{IVM_1974_6_a5,
     author = {I. I. Mel'nik},
     title = {$K$-operatives},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {47--55},
     year = {1974},
     number = {6},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1974_6_a5/}
}