В каком году рубль стал конвертируемой валютой?
The Soviet ruble (; see below for other languages of the USSR) was the currency of the Union of Soviet Socialist Republics (USSR). One ruble was divided into 100 kopeks, (also transliterated as kopecks or copecks – "kopeyka", "kopeyki"). Many of the ruble designs were created by Ivan Dubasov. 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. In addition to regular currency, some other currency units were used, such as several forms of "convertible ruble," transferable ruble, clearing ruble, Vneshtorgbank cheque, etc.; also, several forms of virtual rubles (called "non-cash ruble" or "cachless ruble": "Безналичный рубль" "beznalichny rubl") were used for inter-enterprise accounting and international settlement in the Comecon zone. In 1991, after the breakup of the USSR, the Soviet ruble continued to be used in the post-Soviet states, forming a "ruble zone", until it was replaced with the Russian ruble by 1993.
1991