Columbia subject headings:
Harvard subject headings:
Automobile industry and trade--Germany--History--20th century.
Porsche A.G.--History.
Porsche automobiles--History--20th century.
Volkswagen automobiles--History--20th century.
Princeton subject headings:
Automobile industry and trade--Germany--History--20th century.
Porsche A.G.--History.
Porsche automobiles--History--20th century.
Volkswagen automobiles--History--20th century.