@article{AL_1969_8_3_a7,
     author = {V. G. Sokolov},
     title = {An analogue of {Witt's} formula for free solvable groups},
     journal = {Algebra i logika},
     pages = {367--372},
     publisher = {mathdoc},
     volume = {8},
     number = {3},
     year = {1969},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AL_1969_8_3_a7/}
}