Lewis Siegelbaum and Leslie Moch have published “Transnationalism in One Country? Seeing and Not Seeing Cross Border Migration Within the Soviet Union” in Slavic Review, vol. 75, no. 4 (Winter 2016): 970-986. This is a conceptual piece that extends the notion of the USSR as a “state of nations” to migration within its borders, arguing that in those terms, transnational migration was easier in the USSR than in much of the rest of the world.