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In page Samizdat:
"Ribs, "music on the ribs", "bone records",[1] or roentgenizdat (roentgen- from the Russian term for X-ray, named for Wilhelm Röntgen[2]) were homemade phonograph records, copied from forbidden recordings that were smuggled into the country. Their content was Western rock and roll, jazz, mambo, and other music, and music by banned emigres, such as Pyotr Leshchenko and Alexander Vertinsky. They were sold and traded on the black market.[citation needed]