20F22 2 locally nilpotent radical (generalized) radical group 1 20E34 1 20F16 1 20F16; Secondary 20E25 1 20F18 1 20F19 1 20F50 1 Primary 20E15 1 \(GNA\)-subgroup 1 abnormal subgroup 1 finite special rank 1 locally finite radical 1 locally nilpotent residual 1 normal subgroup 1 periodic group 1 pronormal subgroup 1 self-normalizing subgroup 1 soluble group 1 transitively normal subgroups 1