Steven J. Zaloga, Ramiro Bujeiro, Howard Gerrard, Poland 1939: the birth of blitzkrieg, Osprey Publishing, 2002, ISBN 1-84176-408-6, Google Print, p.50
Telegram: The German Ambassador in the Soviet Union, (Schulenburg) to the German Foreign Office. Moscow, 10 September 1939 – 9:40 p.m. and Telegram 2: he German Ambassador in the Soviet Union (Schulenburg) to the German Foreign Office. Moscow, 16 September 1939. Source: The Avalon Project at Yale Law School. Last. Retrieved 14 November 2006