> This created things like roentgenizdat or "ribs" (gramophone recordings made from polyester X-ray films)

This is a plot point in the excellent Star City, a spin-off of For All Mankind. https://en.wikipedia.org/wiki/Star_City_(TV_series). Also see this project by English musician Stephen Coates: https://www.x-rayaudio.com/

Yeah I edited it out because it had a different name, and more importantly there were totally different circles of people. It wasn't a single underground community or something like that. Later on there were VHS clubs ("video salons"), completely different people again. Some describe all that as samizdat but it really wasn't. Article's mention of Solzhenitsyn in the same sentence with Pajitnov makes little sense.