Professor at Petrograd University and the Pedagogical Institute. Wrote a 2-volume History of Byzantium. Emigrated in the mid 1920s.
Settled in the USA. Became professor at Wisconsin University, 1947, and Zhukovskii, 1950. Codirector with M. Romm on Lenin v Oktiabre, 1937. Assistant to De Santis on Oni Shli Na Vostok, 1967, an Italian-Soviet co-production.