@article{SM_1968_5_3_a9,
     author = {G. I. Kats},
     title = {Extensions of groups to ring groups},
     journal = {Sbornik. Mathematics},
     pages = {451--474},
     year = {1968},
     volume = {5},
     number = {3},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1968_5_3_a9/}
}