Columbia subject headings:
Espionage, British--Soviet Union--History--20th century.
Reilly, Sidney George, 1874-1925.
Secret service--Great Britain--History--20th century.
Soviet Union--History--Revolution, 1917-1921--Secret service.
Spies--Great Britain--Biography.
Spies--Soviet Union--Biography.
Harvard subject headings:
Espionage, British--Soviet Union--History--20th century.
Reilly, Sidney George, 1874-1925
Secret service--Great Britain--History--20th century.
Secret service--Soviet Union--History
Soviet Union--History--Revolution, 1917-1921--Secret service.
Spies--Great Britain--Biography.
Spies--Soviet Union--Biography.
Princeton subject headings:
Espionage, British--Soviet Union--History--20th century.
Reilly, Sidney George, 1874-1925.
Spies--Great Britain--Biography.