20F18 20F19 3 20F16 2 abnormal subgroup 2 normal subgroup 2 pronormal subgroup 2 self-normalizing subgroup 2 (generalized) radical group 1 20E15 1 20E99 1 20F22 1 20F50 1 Abelian-by-nilpotent groups 1 \(GNA\)-subgroup 1 \(G\)-eccentric subgroups 1 \(\mathrm{GNA}\)-subgroup 1 contranormal subgroups 1 hypercenter of a group 1 locally finite group 1 locally finite radical 1 locally nilpotent radical 1 locally nilpotent residual 1 rationally irreducible subgroups 1