@article{IVM_1967_6_a5,
     author = {N. V. Ivanova},
     title = {The relative power of set-theoretic operations},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {43--53},
     publisher = {mathdoc},
     number = {6},
     year = {1967},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1967_6_a5/}
}