Columbia subject headings:
Russia--History--Chronology.
Soviet Union--History--Chronology.
Harvard subject headings:
Russia (Federation)--History--1991---Chronology.
Russia--History--Chronology.
Soviet Union--History--Chronology.
Princeton subject headings:
Russia (Federation)--History--1991---Chronology.
Russia--History--Chronology.
Soviet Union--History--Chronology.