Columbia subject headings:
Harvard subject headings:
Music--Germany--Acoustics and physics--History--20th century.
Radio broadcasting--Germany--Sound effects--History--20th century.
Radio broadcasting--Social aspects--Germany--History--20th century.
Sound--Recording and reproducing--Germany--History--20th century.
Princeton subject headings:
Music--Germany--Acoustics and physics--History--20th century.
Radio broadcasting--Germany--Sound effects--History--20th century.
Radio broadcasting--Social aspects--Germany--History--20th century.
Sound--Recording and reproducing--Germany--History--20th century.