@article{AL_1978_17_4_a1,
     author = {A. F. Krasnikov},
     title = {Nilpotent subgroups of relatively free groups},
     journal = {Algebra i logika},
     pages = {389--401},
     year = {1978},
     volume = {17},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AL_1978_17_4_a1/}
}