@article{DAN_1963_151_1_a18,
     author = {A. L. Shmel'kin},
     title = {Free polynilpotent groups},
     journal = {Doklady Akademii Nauk},
     pages = {73--75},
     publisher = {mathdoc},
     volume = {151},
     number = {1},
     year = {1963},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1963_151_1_a18/}
}