The six-volume Mikrokosmos (1935), consisting of 150 progressively graded piano pieces, constitutes a summary of his development, as do his six string quartets, considered among the most important string quartets after those of Ludwig van Beethoven.
Bartók's other works include the eight Rumanian Dances from Hungary (1915), for piano (also orchestrated and arranged for various instruments); the Allegro barbaro (1911) for piano; the opera Duke Bluebeard's Castle (1911); the ballets The Wooden Prince (1914-16) and The Miraculous Mandarin (1921); Music for Strings, Percussion, and Celesta (1937); and Concerto for Orchestra (1943). Also notable are his violin concerto (1938), Music for Two Pianos and Percussion (1937), and his third piano concerto, concluded by his friend Tibor Serly.