Kabytov, Petr, Edward Dubman, and Olga Leontieva. 2015. “The Middle Volga and Trans-Volga Region in the Context of Development of the Russian State System: A Modern Concept”. Quaestio Rossica, No. 2 (June):117 – 131. https://doi.org/10.15826/qr.2015.2.099.