Columbia subject headings:
Harvard subject headings:
Air defenses--Austria--Vienna--History--20th century.
Air defenses--Germany--Berlin--History--20th century.
Air defenses--Germany--Hamburg--History--20th century.
Fortification--Austria--Vienna--History--20th century.
Fortification--Germany--Berlin--History--20th century.
Fortification--Germany--Hamburg--History--20th century.
World War, 1939-1945--Antiaircraft artillery operations.
Princeton subject headings:
Air defenses--Austria--Vienna--History--20th century.
Air defenses--Germany--Berlin--History--20th century.
Air defenses--Germany--Hamburg--History--20th century.
Fortification--Austria--Vienna--History--20th century.
Fortification--Germany--Berlin--History--20th century.
Fortification--Germany--Hamburg--History--20th century.
World War, 1939-1945--Antiaircraft artillery operations.