Question: Included among chromatic button accordions is what chromatic button accordion developed in Russia in the early 20th century and named after the 11th-century bard Boyan?
Sentence (from "Chromatic button accordion"): The bass-side keyboard is usually the Stradella system or one of the various free-bass systems. Included among chromatic button accordions are the Russian bayan and Schrammel accordion.
Relevant evidence: Yes