Always regretted not purchasing a souvenir book of the Graf Zepplin 'world tour' off a stall at Newark many many years ago. All text in German, but it had fantastic pictures taken from the airship (lots with the shadow of the airship cast onto the ground like a cloud), maps and drawings & diagrams of how it worked etc. As you would expect from a German publication, the quality of the book was top rate. The guy had quite a few bits of airship framing, bits of propellers etc. too. Most unusual gear.