The information for this podcast came primarily from two books:
Bombing Hitler, by Helmut HaasisBombing Hitler: The Story of the Man Who Almost Assassinated the Führer
The Lone Assassin, by Helmut OrtnerLone Assassin: The Epic True Story of the Man Who Almost Killed Hitler
Georg Elser was interrogated many times by the Nazi government. These interrogations were preserved which is why much of what he did is public knowledge and discussed in these books in detail.