Overy, Richard. Russia's War A History of the Soviet War Effort: 1941-1945. New York: Penguin, 1998.
German war plans called for a three pronged lightning advance from the present Polish border by three large forces, Army Group North, Center and South, to a line designated A-A, from Archangel in the north to Astrakhan on the Volga. The aim was to destroy Soviet armed forces west of the A-A line and to deploy frontier fortifications and the Luftwaffe to subjugate the scattered remnants beyond the Urals. The operation was originally scheduled to begin on May 15, but that was later postponed to June 22. The conquest of western Russia was scheduled to take four to six months. The diversion of German forces in the spring of 1941 to conquer Yugoslavia which was brought about by an unexpected coup d'etat by anti-German officers in Belgrade and to eject the British from Greece and later Crete contributed to the five week delay in initiating Barbarossa; but Beevor said other factors were involved: "the exceptionally heavy spring rains, the inability of the Luftwaffe to prepare forward airfields on time, and the allocation of motor transport to divisions" (14).
"Britain's hope lies in Russia and the United States. If
Kershaw, Ian. Hitler 1889-1936 Hubris. New York: Norton, 1999.
Dupuy R. Ernest, and Trevor N. Dupuy. The Encyclopedia of Military History From 3500 B.C. to the Present. New York: Harper & Row, 1986.
Read, Anthony, and David Fisher. Deadly Embrace Hitler, Stalin and the Nazi-Soviet Pact 1939-1941. New York: Norton, 1988.