Columbia subject headings:
Espionage--Germany.
Espionage--Soviet Union.
Lucas, William Otto, 1893-1975.
Harvard subject headings:
Espionage--Germany.
Espionage--Soviet Union.
Lucas, William Otto, 1893-1975.
Princeton subject headings:
Espionage--Biography.
Lucas, William Otto, 1893-1975.
Spies--Great Britain--Biography.