Belyakova, Zoia, , Hazar Publishing, 1994, ISBN 1-874371-27-X. King, Greg & Penny Wilson , Eurohistory, 2006, ISBN McIntosh, David, , in Royalty History Digest. Zeepvat, Charlotte, , in Royalty History Digest. Zeepvat, Charlotte, , in Royalty History Digest. Zeepvat, Charlotte, , Sutton Publishing, 2004, ISBN 0-7509-3049-7.