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

Context paragraphs:
José Cândido de Carvalho: José Cândido de Carvalho was a Brazilian writer born in Campos dos Goytacazes, Rio de Janeiro on August 5, 1914.  His "O Coronel e o Lobisomem" (English: "The Colonel and the Werewolf") was the basis for a TV series and feature film.  He died August 1, 1989

Vsevolod II of Kiev: Vsevolod II Olgovich (Cyrillic: Всеволод II Ольгович) (died August 1, 1146) was the Prince (Knyaz) of Chernigov (1127–1139) and Grand Prince (Velikiy Knyaz) of Kiev (1139–1146), son of Oleg Svyatoslavich, Prince of Chernigov.

Clare West (costume designer): Clare West born Clara Belle Smith May 10, 1889 in Missouri, died August 1, 1980 Ontario, California with some sources stating she was born 30 January, 1879 and dying 13 March, 1961 was one of the first costume designers in Hollywood.  She did notable work in the films of D.W. Griffith and Cecil B. DeMille.  Recognising the importance of film costume in haute couture, some regard her as a predecessor in the American Look.

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.

Jimmy Caci: Vincent Dominic "Jimmy" Caci (born August 1, 1925 – died August 16, 2011) was a Los Angeles crime family member and a Caporegime (Captain) in the family.

Leonid Sagalov: Leonid Sagalov (born in Kharkiv, 1910 - died in Moscow, 1940) was a Soviet pianist.

Maria Grinberg: Maria Grinberg (Russian: Mария Израилевна Гринберг, "Marija Israilevna Grinberg") (September 6, 1908 – July 14, 1978), was a Soviet pianist.  She was born in Odessa, Ukraine, then part of the Russian Empire.  Her father was a Hebrew scholar and her mother taught piano privately.  Until the age of 18, Maria took piano lessons from Odessa's noted teacher David Aisberg.  Eventually she became a pupil of Felix Blumenfeld (who also taught Vladimir Horowitz) and later, after his death, continued her studies with Konstantin Igumnov at the Moscow Conservatory.  In 1935, she won the Second Prize at the Second All-Union Pianist Competition.

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.

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.

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.

Supporting paragraphs: Oleg Kagan Sviatoslav Richter
Answer: Sviatoslav Richter