In 1911, Bartók wrote his only opera, "Bluebeard's Castle". There are only two singers in the opera: Bluebeard and his wife Judith. He also wrote a ballet called "The Wooden Prince". This started to make him famous abroad. Another ballet, "The Miraculous Mandarin", is even more famous today. It shows the influence of Igor Stravinsky, Arnold Schoenberg, as well as Richard Strauss. He wrote a lot of chamber music including a total of 6 string quartets, 2 violin sonatas and a "Sonata for Two Pianos and Percussion". He wrote some pieces for smaller orchestras: "Divertimento for strings" and "Music for Strings, Percussion and Celesta".