20D05 Classification of simple and nonsolvable groups
20D06 Simple groups: alternating groups and groups of Lie type [See also 20Gxx]
20D08 Simple groups: sporadic groups
20D10 Solvable groups, theory of formations, Schunck classes, Fitting classes, $\pi$-length, ranks [See also 20F17]
20D15 Nilpotent groups, $p$-groups
20D20 Sylow subgroups, Sylow properties, $\pi$-groups, $\pi$-structure
20D25 Special subgroups (Frattini, Fitting, etc.)
20D30 Series and lattices of subgroups
20D35 Subnormal subgroups
20D40 Products of subgroups
20D45 Automorphisms
20D60 Arithmetic and combinatorial problems
20D99 None of the above, but in this section