The German balance of payments went strongly negative. In 1933-36 exports declined by 9% in value while imports rose by 9%. - Carr, William Arms, Autarky and Aggression Edward Arnold: London, United Kingdom, 1972 page 53
In the spring and summer of 1936, the reduced availability of foreign currency constrained imports of raw materials, with some key stockpiles falling to only two months' production. - Kershaw, Ian Hitler Nemesis W.W. Norton: New York, New York, United States of America, 2000 page 9
Dr. Schacht informed the War Minister, Field Marshal Werner von Blomberg that lack of lead and copper prevented fulfilling his requests for increased military production. - Carr, William Arms, Autarky and Aggression Edward Arnold: London, United Kingdom, 1972 page 54