20E15 20F19 8 20F50 6 20F22 5 20F16 4 20F18 4 locally finite group 4 pronormal subgroup 4 radical group 4 self-normalizing subgroup 4 20F14 3 subnormal subgroup 3 20-00 2 2019 2 20B07 2 20C07 2 20E07 2 20E25 2 20E26 2 20E28 2 20E34 2 20E34,20E36 2 20E45 2 20F24 2 Baer radical 2 CC – groups 2 Chernikov groups 2 FC – groups 2 Gruenberg radical 2 Modular subgroup lattices 2