A filmmaker's shelf holds four books on one of the least documented chapters of twentieth-century American history: the African Americans — writers, engineers, artists, intellectuals — who traveled to or settled in the Soviet Union between the 1920s and the 1960s, in search of a society that promised what America denied them. Langston Hughes, W.E.B. Du Bois, Paul Robeson, and Robert Robinson. Before these books go into storage, they deserve a post.