Columbia subject headings:
Harvard subject headings:
Radio stations--Germany--History--20th century.
Radio, Military--Germany--History--20th century.
Radio--Germany--Transmitters and transmission--History--20th century.
Soldiers--Recreation--Germany--History--20th century.
Princeton subject headings:
Radio broadcasting--History.
Radio, Military--History.
Radio--Transmitters and transmission--Handbooks, manuals, etc.