Are there any records related to the relations between Turkey and USSR in 1920's? I know about the letter from Ataturk to Lenin (in Turkish) but nothing more.
A public prosecutor's office in İstanbul has reportedly launched a probe into the Atatürkist Thought Association (ADD) over its use of a banner showing Mustafa Kemal Atatürk, the founder of the Republic of Turkey, side by side with Russian revolutionary and communist politician Vladimir Lenin.
For posterity, this was the banner:
In the early 1920s the relationships between the Kemalists and the Bolsheviks were friendly, based on their common fight against "imperialist governments". In 1920, Lenin supplied Ataturk with:
6,000 rifles, over 5 million rifle cartridges, 17,600 projectiles as well as 200.6 kg of gold bullion
...which were essential to Ataturk's Armenian campaign and the Greco-Turkish War (1919 - 1922).
As for documentation, the Treaty of Moscow, signed on 16 March 1921, a time were neither the Soviet Union nor the Republic of Turkey were established, is probably what you're looking for. It established friendly relations between the two countries and defined Turkey's borders with the Soviet Union; those borders are still in existence. A later treaty, the Treaty of Kars (October 13, 1921) re-affirmed the Treaty of Moscow.