Columbia subject headings:
Harvard subject headings:
Nationalism--Spain--País Vasco--History--20th century
País Vasco (Spain)--History--20th century.
Secret service--Spain--País Vasco--History--20th century.
World War, 1939-1945--Secret service--Spain--País Vasco.
Princeton subject headings:
Cold War.
Espionage--Spain--País Vasco--History--20th century.
Nationalism--Spain--País Vasco--History--20th century.
Spain--History--Civil War, 1936-1939--Secret service.
World War, 1939-1945--Secret service--Spain--País Vasco.