J.B.Bury, History of the Eastern Empire from the Fall of Irene to the Accession of Basil 1912, p.408; Kevin Alan Brook, The Jews of Khazaria, ML 20706, 2004, p.29-30
google.co.uk
books.google.co.uk
Yulia Ustinova, The Supreme Gods of the Bosporan Kingdom, Brill 1999, ch.3, p.129ff