William L. Shirer, The Rise and Fall of the Third Reich
Winston S. Churchill, The Gathering Storm
http://www.worldwar-2.net/timelines/war-in-europe/eastern-europe/eastern-europe-index-1939.htm
An RAF Blenheim bomber of 139 Squadron conducts the RAF's first operational sortie of the war when it flew over to Germany to check shipping in the Schillig Roads. With a frozen radio, it was unable to transmit any information back to base and by the time it landed it was too late to mount an attack that day. Later that night, Whitley bombers conduct an number of leaflet dropping sorties over Germany.
http://www.worldwar-2.net/timelines/war-in-europe/european-air-war/european-air-war-index-1939.htm
The Kriegsmarine begins its campaign against British merchant shipping with 17 U-boats putting to sea out of a total of about 57 operational boats, far fewer than the 300 Dönitz had felt he needed to succeed against Britain.
http://www.worldwar-2.net/timelines/war-at-sea/atlantic/battle-of-the-atlantic-index-1939.htm