You would measure the length of a jump rope in feet
So that the Panama Canal could be built. This would make it easier for the United States to move their ships from the Atlantic to the Pacific and vice versa.
Answer:
Letters and publications written by Nazi leaders before the Second World War.
Explanation:
This answer is correct because this historian is searching for the motives of these perpetrators, letters and publications can tell their thoughts and conversations.
There is not an exact answer, but I believe it is millions.
