20F22 20F50 9 20E34 7 20F19 7 20E15 5 locally nilpotent radical 5 finite special rank 4 locally nilpotent residual 4 periodic group 4 soluble group 4 transitively normal subgroups 4 20F16 3 20F16; Secondary 20E25 3 20F18 3 20H20 3 Primary 20E15 3 locally finite group 3 self-normalizing subgroup 3 20-00 2 20B07 2 20C07 2 20E07 2 20E25 2 20E26 2 20E28 2 20E34,20E36 2 20E45 2 20F14 2 20F16; Secondary: 20E25 2 20F24 2