  A complete classification of finitely generated involutive commutative
two-valued groups is obtained. Three series of such two-valued groups are
constructed: principal, unipotent and special, and it is shown that any
finitely generated involutive commutative two-valued group is isomorphic to a
two-valued group belonging to one of these series. A number of classification
results are obtained for topological involutive commutative two-valued groups
in the Hausdorff and locally compact cases. The classification of algebraic
involutive two-valued groups in the one-dimensional case is also discussed.
