@article{MZ_1968__103_170907,
     author = {Frank Levin},
     title = {On {Some} {Varieties} of {Soluble} {Groups.} {II.}},
     journal = {Mathematische Zeitschrift},
     pages = {162--172},
     publisher = {mathdoc},
     volume = {103},
     year = {1968},
     zbl = {0155.04502},
     url = {http://geodesic.mathdoc.fr/item/MZ_1968__103_170907/}
}