Columbia subject headings:
Soviet Union--Politics and government--1917-1936--Sources.
Trotsky, Leon, 1879-1940.
Harvard subject headings:
Kommunisticheskai︠a︡ partii︠a︡ Sovetskogo Soi︠u︡za--History--Sources.
Opposition (Political science)--Soviet Union--History--Sources.
Soviet Union--Politics and government--1917-1936--Sources.
Trotsky, Leon, 1879-1940--Archives.
Princeton subject headings:
Soviet Union--History--1917-1936--Sources.
Soviet Union--Politics and government--1917-1936--Sources.
Trotsky, Leon, 1879-1940--Archives.