Question: Are Sergei Prokofiev and Modest Mussorgsky both Soviet composers?
Sentence (from "Sergei Prokofiev"): Of the established forms and genres in which he worked, he created – excluding juvenilia – seven completed operas, seven symphonies, eight ballets, five piano concertos, two violin concertos, a cello concerto, a Symphony-Concerto for cello and orchestra, and nine completed piano sonatas.
Relevant evidence: No