Columbia subject headings:
Harvard subject headings:
Disasters--Political aspects--Soviet Union--History--20th century.
Disasters--Social aspects--Soviet Union--History--20th century.
Disasters--Soviet Union--History--20th century.
Soviet Union--History.
Princeton subject headings:
Disasters--Political aspects--Soviet Union--History--20th century.
Disasters--Social aspects--Soviet Union--History--20th century.
Disasters--Soviet Union--History--20th century.
Soviet Union--History.