The Pan Am Clipper: The History of Pan American's Flying Boats 1935–1945 by Roy Allen (2018)
The history of Pan American Airways is, to a great degree, the story of international air transport and, within that, the flying-boat is one of the airliner’s most recognizable aircraft.
The Pan Am Clipper covers one of aviation history’s most inspiring and magical periods. Illustrated with more than 100 archive photographs, this impressive book is a tribute to a technical wonder that continues to fascinate and captivate many people today.
https://www.amazon.com/Pan-Am-Clipper-Americans-1935-1945/dp/1782746048