Columbia subject headings:
Mineral industries--Soviet Union--History.
Soviet Union--Economic policy--1928-1932.
Soviet Union--Economic policy--1933-1937.
Harvard subject headings:
Mineral industries--Soviet Union--History.
Soviet Union--Economic policy--1928-1932.
Soviet Union--Economic policy--1933-1937.
Princeton subject headings:
Mineral industries--Soviet Union--History.
Soviet Union--Economic policy--1928-1932.
Soviet Union--Economic policy--1933-1937.