@article{ZNSL_2007_349_a1,
     author = {N. A. Vavilov and A. K. Stavrova},
     title = {Basic reductions for the description of normal subgroups},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {30--52},
     publisher = {mathdoc},
     volume = {349},
     year = {2007},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_2007_349_a1/}
}