Question: Which of russian composer Igor Stravinsky's works was once conducted by Eduard Flipse, and featured avant-garde natured music?
Context: Eduard Flipse (26 February 1896 in Wissenkerke – 12 September 1973 in Breda) was a Dutch conductor and composer, the son of Cornelis Flipse and Geertje Kruis.  He was noted as a champion of the music of Dutch composers, such as Léon Orthel.  He prepared the chorus for one of the earliest Dutch performances of William Walton's cantata "Belshazzar's Feast".  He was the first Dutch conductor of Igor Stravinsky's "The Rite of Spring" and of the violin concerto of Alban Berg. The Rite of Spring (French: Le Sacre du printemps ; Весна священная, "Vesna svyashchennaya", "sacred spring" ) is a ballet and orchestral concert work by the Russian composer Igor Stravinsky.  It was written for the 1913 Paris season of Sergei Diaghilev's Ballets Russes company; the original choreography was by Vaslav Nijinsky, with stage designs and costumes by Nicholas Roerich.  When first performed, at the Théâtre des Champs-Élysées on 29 May 1913, the avant-garde nature of the music and choreography caused a sensation and a near-riot in the audience.  Although designed as a work for the stage, with specific passages accompanying characters and action, the music achieved equal if not greater recognition as a concert piece, and is widely considered to be one of the most influential musical works of the 20th century. The Concerto for Two Pianos (sometimes also referred to as Concerto for Two Solo Pianos or rather as its Italian original name, Concerto per due pianoforti soli) is a composition by Russian composer Igor Stravinsky.  It was finished on November 9, 1935 and, together with his Sonata for Two Pianos, is considered nowadays as one of his major compositions for piano during his neoclassical period.  It was also Stravinsky's first work after becoming a French citizen. The Stravinsky Fountain (French:" La Fontaine Stravinsky") is a whimsical public fountain ornamented with sixteen works of sculpture, moving and spraying water, representing the works of composer Igor Stravinsky.  It was created in 1983 by sculptors Jean Tinguely and Niki de Saint Phalle, and is located on Place Stravinsky, next to the Centre Pompidou, in Paris. Igor Engraver is a music notation program for the Macintosh and Windows operating systems, created by Swedish composer Peter Bengtson and published by the Swedish company NoteHeads.  Bengtson stated on the Igor-Talk mailing list that he named Igor after the stock character in various horror movies (including the Frankenstein films) as well as to commemorate the Russian composer Igor Stravinsky. Vera de Bosset Stravinsky (January 7, 1889 – September 17, 1982) was a Russian-born American dancer and artist.  She is better known as the mistress and, ultimately, second wife of the Russian composer Igor Stravinsky, who married her in 1940. Serenade in A is a composition for solo piano by Russian composer Igor Stravinsky.  It was completed on September 9, 1925, in Vienna, and published by Boosey & Hawkes This work was composed as a result of his signing his first recording contract for Brunswick, so Stravinsky wrote the piece in a way that each movement would fit on one side of a 78 rpm gramophone record.  It was dedicated to his wife. Sonata for Two Pianos is a composition by Russian composer Igor Stravinsky, premiered in 1944 by Richard Johnston and Nadia Boulanger.  First conceived as a solo work, Stravinsky needed to write it for four hands to voice all four melodic lines clearly.  It is considered one of Stravinsky's most important compositions for two solo pianos, together with Concerto for Two Pianos. Tango is a 1940 piece originally composed for piano by Russian composer Igor Stravinsky.  It is one of Stravinsky's most recorded works for piano. Scherzo à la russe is a 1944 composition by Russian composer Igor Stravinsky.  It was initially published by Chappell & Co. in 1945 and premiered in March 1946 by the San Francisco Symphony Orchestra, conducted by the composer himself.  It was later published by Boosey & Hawkes.
Answer: The Rite of Spring