# Join of two finite subnormal subgroups is subnormal

## History

This result was proved by Wielandt in *Eine Verallgemeinerung der invarianten Untergruppen. Math. Z.45, 209–244 (1939).*

## Statement

Suppose and are two Finite subnormal subgroup (?)s of a group . Then, the join of and is also a Subnormal subgroup (?) of .