@article{SM_1989_63_2_a8,
     author = {I. I. Parovichenko},
     title = {On the topological strength of set-theoretic operations},
     journal = {Sbornik. Mathematics},
     pages = {393--404},
     publisher = {mathdoc},
     volume = {63},
     number = {2},
     year = {1989},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1989_63_2_a8/}
}