Soviet Eras and Constitutions:

Tsar Alexander the 2nd: 1855-1881 (pre-USSR)
Ruled the Russian Empire and was Grand Duke of Finland

Vladimir Lenin: 1917-1924

Joseph Stalin: 1922-1953

Nikita Khrushchev: 1953-1964

Leonid Brezhnev: 1964-1982

Mikhail Gorbachev: 1985-1991

For more about Russian Constituionalism read my paper (pdf file).