︠I︡Uzhna︠i︡a Aravi︠i︡a v rannee srednevekovʹe : stanovlenie srednevekovogo obshchestva - Piotrovskiĭ, M. B. (Mikhail Borisovich) (Izd-vo "Nauka," Glav. red. vostochnoĭ lit-ry, 1985)