@article{PFMT_2018_2_a11,
     author = {V. N. Tyutyanov and T. V. Tihonenko and P. V. Bychkov},
     title = {Product of two $\mathbb{P}$-subnormal subgroups},
     journal = {Problemy fiziki, matematiki i tehniki},
     pages = {80--84},
     publisher = {mathdoc},
     number = {2},
     year = {2018},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/PFMT_2018_2_a11/}
}