Complex sentence: The production of Soviet rubles was the responsibility of the Federal State Unitary Enterprise, or Goznak, which was in charge of the printing of and materials production for banknotes and the minting of coins in Moscow and Leningrad.
Split into simpler sentences: The production of Soviet rubles was the responsibility of the Federal State Unitary Enterprise, or Goznak. Which was in charge of the printing of and materials production for banknotes and the minting of coins in Moscow and Leningrad.