locally graded group 2 20E15 1 20E34 1 20F19,20F22 1 20F22 1 20H20 1 Chernikov group 1 abnormal subgroups 1 contranormal subgroup 1 group 1 locally finite group 1 normal subgroup 1 normal subgroups 1 permutable subgroups 1 pronormal subgroups 1 radical group 1 soluble group 1 subgroup 1 subnormal subgroup 1 transitivity of normality 1