@article{MZ_1970__117_171407,
     author = {James E. Roseblade},
     title = {The {Derived} {Series} of a {Join} of {Subnormal} {Sugroups.}},
     journal = {Mathematische Zeitschrift},
     pages = {57--69},
     publisher = {mathdoc},
     volume = {117},
     year = {1970},
     zbl = {0224.20034},
     url = {http://geodesic.mathdoc.fr/item/MZ_1970__117_171407/}
}