Columbia subject headings:
Espionage, Russian--History.
Intelligence service--Russia--History--20th century.
Russia--Foreign relations--1894-1917.
Spies--Russia--History.
Harvard subject headings:
Espionage--Russia--History.
Intelligence service--Russia--History--20th century.
Russia--Foreign relations--1894-1917.
Spies--Russia--History.
Princeton subject headings:
Espionage--Russia--History.
Russia--Foreign relations--1894-1917.
Spies--Russia--History.