Belova, Svetlana V., et al. “Danube Bulgarians and Volga Bulgars in the Intellectual History of Russia of the 19th Century: The Case of Yuri Venelin and Andrei Likhachev”. Revista Publicando, vol. 5, no. 16 (1), July 2018, pp. 640-7, https://revistapublicando.org/revista/index.php/crv/article/view/1531.