Passing references to 20-century historical figures. Adolf Hitler (1889-1945) was chancellor of Nazi Germany during the latter years of the Depression and the Second World War. Albert Einstein (1879-1955) was a German theoretical physicist and philosopher responsible for the General and Special Theories of Relativity, and the father of modern physics.
Leonid Brezhnev (1906-1982) led the Soviet Union as First Secretary of the Communist Party during the Cold War -- including the period when Prague was invaded by the Soviet Union and Unbearable Lightness takes place. (Brezhnev is shown here during his visit to President Nixon in the U.S., June 19, 1973.)
Aleksandr Solzhenitsyn (1918-2008) was the Russian author of such novels as One Day in the Life of Ivan Denisovich and The First Circle, and the three-volume history The Gulag Archipelago.