1. See Encyclopaedia Judaica, Vol. 5 (Keter, Jerusalem, 1972, pp. 401-410).
2. See http://www.jewishgen.org/Belarus/rje_a.htm.
3. See Jewish-American History and Culture: An Encyclopedia, edited by Jack Fischel and Sanford Pinsker (Garland, New York, NY, 1992, pp. 83-85).
4. See The Jewish Lists, by Martin Greenberg (Schocken, New York, 1979, pp. 210-214).
5. See The Jewish Encyclopedia (Funk and Wagnalls, New York and London, 1903, pp. 16-21).
6. See Jewish Chess Masters on Stamps, by Felix Berkovich (McFarland, Jefferson, NC, 2000).
7. According to recently unsealed FBI files and other independent archival sources, Bobby Fischer's biological father was not the German physicist Hans-Gerhardt Fischer, as previously supposed, but rather the Hungarian-Jewish fluid dynamicist Paul Nemenyi, making both of his parents Jewish. See "Life is not a Board Game," by Peter Nicholas and Clea Benson, The Philadelphia Inquirer, 8 February, 2003. Additional information can be found in Bobby Fischer Goes to War: How the Soviets Lost the Most Exraordinary Chess Match of All Time, by David Edmonds and John Eidinow (HarperCollins, New York, 2004, pp. 313-321). This reference, incidentally, states (p. 39) that Boris Spassky told its authors that there is "no truth" to the widely reported claim that his mother was Jewish.
8. See The Concise Dictionary of American Jewish Biography: Volume One, edited by Jacob Rader Marcus and Judith M. Daniels (Carlson Publishing, Brooklyn, NY, 1994, p. 304).
9. Jewish father, non-Jewish mother.
10. "Of mainly Jewish descent"; see The YIVO Encyclopedia of Jews in Eastern Europe, edited by Gershon David Hundert (Yale University Press, New Haven and London, 2008, Vol. 1, p. 316).
11. See The Concise Dictionary of American Jewish Biography: Volume Two, edited by Jacob Rader Marcus and Judith M. Daniels (Carlson Publishing, Brooklyn, NY, 1994, p. 513).
12. Jewish mother, non-Jewish father. It should be noted that there is considerable controversy over this claim. It should also be noted that in the late 1970s, when Viktor Korchnoi defected from the USSR and leveled charges of rampant anti-Semitism in the Soviet chess establishment, Soviet government newspapers, in an apparent effort to counter those charges, published lists of Soviet Jewish chess luminaries whose successful careers, it was claimed, proved the absence of any such bias. Those lists of Jewish, or partly Jewish, players included Vasily Smyslov. (They did not include Boris Spassky.)
14. Jewish Chronicle (London, 16 August 1985, p.1).
15. Brother of Lajos Steiner.
16. There are many conflicting stories in circulation concerning Johannes Zukertort's background. A Polish language biography, Arcymistrz z Lublina (Grandmaster from Lublin: Truth and Legend about Johannes Hermann Zukertort), by Cezary Domanski and Tomasz Lissowski (Wydawnictwo Szachowe "Penelopa," Warsaw, 2002), makes it clear, however, that Zukertort was the product of an apostate Polish-Jewish family. Zukertort’s father, Jakub (or Yankel) Ezechil Cukertordt (or Cukiertort), was a missionary in the employ of the London Society for Promoting Christianity Amongst the Jews, according to William Thomas Gidney's history of the Society. Domanski and Lissowski report on p. 16 of their book that Jakub Cukiertort converted from Judaism to Christianity on August 28, 1831. JRI-Poland (Jewish Records Indexing – Poland) contains a record of the 1833 divorce of Jakub Ezechil Cukertordt and his first wife, Etla (or Etty) Cukertordt (née Margules or Margulis). Etla has been mistakenly identified as the mother of Johannes, who was born nearly a decade after her divorce from Zukertort's father. Domanski and Lissowski report on pp. 19-20 that shortly after the divorce, Jakub married another convert, Pauline Heilbronn, who would become Johannes’ mother. The Baroness Krzyzanowska as Zukertort's supposed mother is pure fantasy.
18. Former Israeli GM, presently Swiss.
19. See Ismerjük''oket?: zsidó származású nevezetes magyarok arcképcsarnoka, by István Reményi Gyenes (Ex Libris, Budapest, 1997, p. 192).
20. Jewish father (Boris Sheinin), non-Jewish mother.
21. Son of Dr. George Tarjan, 112th President of the American Psychiatric Association, who "was raised in an intellectual, liberal Jewish family" in Hungary, where his parents and younger brother Endre perished in the Holocaust; see obituary in the American Journal of Psychiatry (150:5, May 1993, pp. 691-694).
22. Jewish father (Grigory Aronov), non-Jewish mother.
23. Buried in East Ham Jewish Cemetery; see http://www.theus.org.uk/gravesearch.
24. See Learn from Michal Krasenkow, by Michal Krasenkow (Thinkers Publishing, Belgium, 2019, pp. 9, 12).
25. See 2021 article in the Guardian: "Nepomniachtchi sets up World Chess Championship date with Carlsen."