Columbia subject headings:
Harvard subject headings:
Porsche 911 automobile--History--20th century.
Porsche 911 automobile--History--21st century.
Porsche automobiles--History--20th century.
Porsche automobiles--History--21st century.
Sports cars--Germany--History--20th century.
Sports cars--Germany--History--21st century.
Princeton subject headings:
Porsche 911 automobile--History--20th century.
Porsche 911 automobile--History--21st century.
Porsche automobiles--History--20th century.
Porsche automobiles--History--21st century.
Sports cars--Germany--History--20th century.
Sports cars--Germany--History--21st century.