Miller, Donald L.; Commager, Henry Steele (2001). The Story of World War II. New York: Simon and Schuster. ISBN 978-0743227186. Ueberschär, Gerd R. "The Involvement of Scandinavia in the Plans for Barbarossa". In Boog et al. 1998. Weeks, Albert (2002). Stalin's Other War: Soviet Grand Strategy, 1939–1941. Rowman & Littlefield. ISBN 978-0-7425-2191-9. Hitler's input has been heavily criticised, not least by his generals at the time. Moscow was always a more important objective to the German High Command than it was to Hitler, who was more concerned with destroying Soviet field armies and capturing vital industrial resources. His switching of the main thrust from the central front to Leningrad in the north and Ukraine in the south was to an extent militarily sensible given the weakness of Army Group Centre after the Smolensk battles and the threats to its flanks. Indeed, the diversion actually worked in the Germans’ favour since it surprised the Soviets and resulted in the destruction of huge Soviet forces around Kiev. But it also threw away Germany's only real chance of outright victory. Kirchubel, Robert (2005). Operation Barbarossa 1941: Army Group North. Osprey Publishing. ISBN 978-1-84176-857-1.

Through October is the Soviet autumn. So what happens is you have snowfalls, thaw, snowfall, thaw, you get a completely muddy morass across all of central Russia. So the German offensive begins to grind to a halt both because they're coming up against this new defensive line that they didn't really expect. Plus the Soviet weather's getting in the way, plus the fact that now most German formations especially the armoured formations at the tip of the spear are now down to about 50 strength. They get to 20 kilometers away from Moscow and by that stage, the weather is now turned completely it's now full-blown Soviet winter. By the end of November, you've got more German troops in hospital with frostbite than you have with wounds. And they launched this big Soviet counter-offensive in front of the gates of Moscow and catch the Germans completely by surprise and force them onto the retreat and that's the end of Barbarossa. One of the tenets of that ideology was the idea of 'lebensraum or 'living space'. The creation of a Germanic Aryan Empire in Eastern Europe that would grant the resources needed for self-sufficiency. Having defeated France and the Low Countries in just six weeks, Germany was confident of capturing that land from the Soviet Union. Hitler believed that communist society was fundamentally weak and that it wouldn't take much to defeat it. Hitler by now had lost faith in battles of encirclement as large numbers of Soviet soldiers had escaped the pincers. [249] He now believed he could defeat the Soviet state by economic means, depriving them of the industrial capacity to continue the war. That meant seizing the industrial centre of Kharkov, the Donbas and the oil fields of the Caucasus in the south and the speedy capture of Leningrad, a major centre of military production, in the north. [251] Grazhdan, Anna (director); Artem Drabkin & Aleksey Isaev (writers); Valeriy Babich, Vlad Ryashin, et al. (producers) (2011). Siege of Leningrad (television documentary). Soviet Storm: World War II in the East. Star Media . Retrieved 15 May 2015.Glantz, David (2010a). Barbarossa Derailed: The Battle for Smolensk, Volume 1. Helion & Company. ISBN 978-1906033729.

Glantz, David (2002). Slaughterhouse: The Encyclopedia of the Eastern Front. Garden City, NY: The Military Book Club. ISBN 978-0-73943-128-3. While the Germans underestimated the military potential of their opponents, they also exaggerated the capabilities of their own forces, most significantly the four Panzer Groups. The panzer divisions were the principal weapon of Blitzkrieg and at that time were far superior to the Soviets in training, leadership and tactical ability. But they were relatively weak in numbers and equipment. Hilberg, Raul (1992). Perpetrators, Victims, Bystanders: The Jewish Catastrophe, 1933–1945. New York: Harper Collins. ISBN 0-8419-0910-5. Army units also participated in separating Jewish POWs and commissars in the camps so that they could be murdered. Military Participation in the Economy and Forced Labor Not all military personnel agreed with Nazi policy. Some protested while others actively rescued Jews. While these honorable individuals constituted a statistically small minority, they demonstrated that it was possible to resist and help Jews, even in the disciplined and authoritarian army structure.Clark, Lloyd (2012). Kursk: The Greatest Battle: Eastern Front 1943. Headline Review. ISBN 978-0755336395. Hayward, Joel (1995). "Hitler's Quest for Oil: The Impact of Economic Considerations on Military Strategy, 1941–42". Journal of Strategic Studies. 18 (4): 94–135. doi: 10.1080/01402399508437621.