On p.259 of my book, I briefly discuss the controversy over the supposed discovery of the gravestone of "Isaac Sangari," by Abraham Firkovich in the nineteenth-century in terms of belief about the authorship of the Kuzari.
In the course of my research, I missed this fascinating article on the affair:
Dan Shapira, "Yitshaq Sangari, Sangarit, Bezalel Stern, and Avraham Firkowicz: Notes on Two Forged Inscriptions," Archivum Eurasiae Medii Aevi 14 (2002-2003): 293-317.
I thank Daniel Lasker of Ben Gurion University for the reference. Professor Lasker also tells me that more information is available in Shapira's new book: Matsevot bet ha-ʻalmin shel ha-Yehudim ha-Ḳaraʻim be-Ts’ufuṭ-Ḳalʻeh, Ḳrim (Jerusalem, 2008).
Mikhail Kizilov informs me about his two co-authored articles and his new book from Brill:
Kizilov, Mikhail, and Diana Mikhaylova. “The Khazar Kaganate and the Khazars in European Nationalist Ideologies and Scholarship.” Archivum Eurasii Medii Aevi 14 (2005): 31-53.
Kizilov, Mikhail, Diana Mikhailova. „Khazary i Khazarskii kaganat v evropeiskikh
natsionalisticheskikh ideologiiakh i politicheski orientirovannoi nauchno issledovatel’skoi literature.” Khazarskii Al’manakh 3 (Khar’kov, 2004): 34-62.
Mikhail Kizilov, The Karaites of Galicia: An Ethnoreligious Minority Among the Ashkenazim, the Turks, and the Slavs, 1772-1945. Leiden: Brill, 2009.