>Soviet Archives
Reminder: There is no monolithic Soviet archives. It's an umbrella term usually to refer to the over a dozen central state archives in Moscow, which over the course of several mergers, acquisitions, and Renamings got the main previously classified government records and communist party records. Certain collections are open to the public. Other archives might be invitation only or by request of scholars. There are certain records that to this day are still classified, especially retaining to some of the operations of the Cheka, NKVD, and KGB are deemed to still be relevant to Russian national security and are usually within the FSB archives. The term could also include regional and local archives across the country and in other former Soviet countries. In the broadest sense it could even refer to archives completely outside the former Soviet Union, which have a Soviet documentary focus.
So just keep that in mind any time anyone refers to "the soviet archives" in a casual conversation. Maybe interrogate what they mean by that, regardless of whose "side" they appear to be on.