szerk.: May: The Mongol Empire: A Historical Encyclopedia, Empires of the World. Santa Barbara, California: ABC-CLIO, 65. o.. ISBN 9781610693400. Hozzáférés ideje: 2019. augusztus 21. „During the Mongol invasion of the Rus' principalities in 1238-1240, Novgorod escaped destruction by the Mongols due to an early spring, which transformed the routes to Novgorod into a muddy bog.”
Pinkus, Oscar. Death of Barbarossa, The War Aims and Strategies of Adolf Hitler. Jefferson, North Carolina: McFarland, 241. o.. ISBN 9780786420544. Hozzáférés ideje: 2019. augusztus 21. „By the time the Germans approached their major objectives such as Rostov, Moscow, or Leningrad the campaigning season was over and Barbarossa was off his horse. [...] [Hitler] had not planned to fight in Russia during the fall and winter. He had stated in his Directive No. 21 that this was to be a 'lightning campaign' to be won in two to four months maximum. [...] the cause of failure was the proposition that the Soviet Union could and would be defeated in a blitzkrieg.”
edwardtufte.com
M. Adolphe Thiers. History of the Consulate and the Empire of France under Napoleon ford.: D. Forbes Campbell:. Philadelphia: J. B. Lippincott & Co, 243. o. (1864. június 21.) „whilst it was almost impossible to drag the gun-carriages through the half-frozen mud” (regarding November 20, 1812)
