@article{PFMT_2012_1_a18,
     author = {V. M. Sel'kin},
     title = {On one property of the product of non-identity formations},
     journal = {Problemy fiziki, matematiki i tehniki},
     pages = {101--104},
     publisher = {mathdoc},
     number = {1},
     year = {2012},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/PFMT_2012_1_a18/}
}