@article{AL_1971_10_6_a2,
     author = {M. I. Kargapolov and V. A. Churkin},
     title = {Varieties of solvable groups},
     journal = {Algebra i logika},
     pages = {651--657},
     publisher = {mathdoc},
     volume = {10},
     number = {6},
     year = {1971},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AL_1971_10_6_a2/}
}