Question: Oleg Moiseyevich Kagan collaborated with which Soviet pianist who died August 1, 1997?

full_context: Document 1: Sviatoslav Richter: Sviatoslav Teofilovich Richter (Russian: Святосла́в Теофи́лович Ри́хтер , "Sviatosláv Teofílovich Ríkhter"; ] ; March 20 [O.S. March 7] 1915 – August 1, 1997) was a Soviet pianist known for the depth of his interpretations, virtuoso technique, and vast repertoire. He is considered one of the greatest pianists of the 20th century.
Document 2: Vladimir Horowitz discography: The Russian-American classical virtuoso pianist Vladimir Horowitz was a recording artist for over 60 years; beginning in 1926 on a piano roll system for Welte-Mignon, then with audio recordings, starting in 1928 for the Victor Talking Machine Company, later RCA Victor. Horowitz continued to record for a variety of record labels throughout his life. Between 1962 and 1973 he recorded for Columbia Masterworks In 1975, Horowitz returned to RCA, with which he recorded a series of live recitals. For the last years of his life, between 1985 and 1989, Horowitz recorded for Deutsche Grammophon. Horowitz’s final recording, with Sony Classical, was completed in November 1989, four days before his death. This final recording consisted of repertoire that he had never previously recorded.
Document 3: Georg Kulenkampff: Alwin Georg Kulenkampff-Post (23 January 1898 – 4 October 1948) was a German virtuoso violinist. One of the most popular German concert violinists of the 1930s and 1940s, he was considered one of the finest violinists of the 20th century.
Document 4: Yehudi Menuhin: Yehudi Menuhin, Baron Menuhin, (22 April 191612 March 1999) was an American-born violinist and conductor who spent most of his performing career in Britain. He is widely considered one of the greatest violinists of the 20th century.
Document 5: Dmitri Shostakovich: Dmitri Dmitriyevich Shostakovich (Russian: Dmitriy Dmitrievich Shostakovich , ] ; 25 September [O.S. 12 September] 1906 9 August 1975) was a Russian composer and pianist. He is regarded as one of the major composers of the 20th century.
Document 6: Piano Sonata No. 9 (Prokofiev): Sergei Prokofiev's Piano Sonata No. 9 in C major, Op. 103 (1947) is a sonata for solo piano composed in 1947 and consists of four movements. The sonata was dedicated to Sviatoslav Richter, a member of the Union of Soviet Composers, and by whom it was first performed on 21 April 1951 in Moscow.
Document 7: Sergei Rachmaninoff: Sergei Vasilievich Rachmaninoff (Russian: Серге́й Васи́льевич Рахма́нинов , "Sergey Vasilyevich Rakhmaninov"; ] ; 1 April [O.S. 20 March] 1873 28 March 1943) was a Russian virtuoso pianist, composer, and conductor of the late-Romantic period, some of whose works are among the most popular in the romantic repertoire.
Document 8: Jakub Kagan: Jakub Kagan (7 February 1896 – 1942) was a popular Polish-Jewish composer, pianist, jazz musician and arranger. In the early 1920s, he formed the Kagan's Jazz Band in Warsaw, performing in operettas, cabarets, and hotels. Since 1922 Kagan was a feature artist at the Kabaret Mirage and at the Teatr Nowości. In 1926 he signed a contract with the luxury Hotel Bristol in Warsaw. His band performed world-renowned standards as well as his own compositions widely popular across the country. He died in Warsaw during the Holocaust in occupied Poland.
Document 9: Vanya Milanova: Vanya Milanova was born on January the 12th 1954. She is an internationally renowned solo violinist and recording artist. She is noted for being a female breakthrough artist in a male dominated field. Her beauty of tone, technical ability and having an unusually large repertoire have been much commentated on in press reviews. She has made a lasting impact on violin performing through being the very first woman to record the entire 24 Paganini caprices in a primarily male field for the Simax Label, Oslo, 1985. She performed works which were often only attributed to male soloists. Bulgarian born, Vanya Milanova was a child prodigy, having performed her first paid concert at the age of three. She studied at the Music School in Sofia and the State Music Academy in Sofia in the class of Peter Arnaudov and later at the Guildhall School of Music in London where she studied with pedagogue Yfrah Neaman OBE. Before turning 20 years of age she had already won prizes at many of the major competitions: Tchaikovsky, Queen Elizabeth and Paganini. She has played with some of the best orchestras in England, France, Italy, Turkey, Israel, Portugal, Sweden, Norway, Denmark, South America and South Africa. She has made frequent recordings with the BBC – London and Manchester, Norwegian Label Simax and the Italian Label Real Sound. and has played at the Royal Festival Hall, Wigmore Hall, the Royal Albert Hall and the Royal Opera House for the Edward Boyle Memorial Concert 1983 attended by Her Royal Majesty the Queen in aid of the Edward Boyle Memorial Trust, featuring Vanya Milanova, the Amadeus String Quartet, Murray Perahia, Kathryn Scott and Dame Janet Baker). Vanya Milanova has been awarded 'Freedom of the City Award' in her native Bulgaria for her outstanding contribution to music and popularising classical music to a younger generation. Alongside being a performing and recording artist, She was violin professor at Bilkent University, Turkey and at various other institutions where she disseminated her style to a new generation of young violinists.
Document 10: Heinrich Neuhaus: Heinrich Gustavovich Neuhaus (Russian: Ге́нрих Густа́вович Нейга́уз , "Genrikh Gustavovič Nejgauz"; 12 April [O.S. 31 March] 1888 10 October 1964) was a Soviet pianist and pedagogue of German extraction. He taught at the Moscow Conservatory from 1922 to 1964. He was made a People's Artist of the RSFSR in 1956. His pedagogic book "The Art of Piano Playing" (1958) is regarded as one of the most authoritative and most widely used treatments on the subject. He died in Moscow in 1964.
Document 11: Oleg Kagan: Oleg Moiseyevich Kagan (Russian: Оле́г Моисе́евич Кага́н; 22 November 1946 Yuzhno-Sakhalinsk, Russian SFSR – 15 July 1990, Munich, West Germany) was a Soviet violinist, known for his chamber collaborations with such musicians as pianist Sviatoslav Richter and cellist Natalia Gutman, his wife. He was also a significant proponent of modern music, in particular Berg's Violin Concerto. Several recently released concert recordings have added to his posthumous reputation.
Document 12: Frank Bungarten: Frank Bungarten is a classical guitarist from Germany. Born in Cologne in 1958, Bungarten had his early influence of Guitar music when he was a teenager. In 1981, he got noticed in the international guitar scene, when virtuoso guitarist Andrés Segovia honored him with the first prize at the Guitar Competition of Granada, combined with an extensive concert tour of Spain. To date, he has performed in more than 40 countries. Among his recordings, “J.S.Bach ~ Sonatas and Partitas for Violin solo”, got serious recognition. Although he is often regarded as a Bach expert on the Concert Guitar, Bungarten claims to love and play a wide & diverse repertoire.
Document 13: Emil Gilels: Emil Grigoryevich Gilels (sometimes transliterated "Hilels"; , Russian: Эми́ль Григо́рьевич Ги́лельс , "Emiľ Grigorievič Gileľs "; 19 October 1916 – 14 October 1985) was a Soviet pianist, widely regarded as one of the greatest pianists of the 20th century.
Document 14: Glenn Gould: Glenn Herbert Gould ( ; 25 September 19324 October 1982) was a Canadian pianist who became one of the best-known and most celebrated classical pianists of the 20th century. He was particularly renowned as an interpreter of the keyboard music of Johann Sebastian Bach. His playing was distinguished by remarkable technical proficiency and capacity to articulate the polyphonic texture of Bach's music. He is widely considered one of the greatest pianists of the 20th century.
Document 15: Niccolò Paganini: Niccolò (or Nicolò) Paganini (] ; 27 October 178227 May 1840) was an Italian violinist, violist, guitarist, and composer. He was the most celebrated violin virtuoso of his time, and left his mark as one of the pillars of modern violin technique. His 24 Caprices for Solo Violin Op. 1 are among the best known of his compositions, and have served as an inspiration for many prominent composers.
ground_truth: Sviatoslav Richter