Columbia subject headings:
Russians--Political activity--Europe.
Secret service--Russia.
Secret service--Soviet Union.
Soviet Union--Politics and government--1917-1936.
Harvard subject headings:
Russians--Europe--Political activity.
Secret service--Russia.
Secret service--Soviet Union
Soviet Union--Politics and government--1917-1936.
Princeton subject headings:
Russia--Politics and government--1894-1917.
Russians--Europe--Political activity.
Secret service--Russia.