Dem's book was part of the flood of Ancient Astronaut books inspired by the huge success of Erich von Daniken's Chariots of the Gods?
Erich con Daniken was not an author. 
mnli hypothesis: Erich con Daniken was not an author.  premise: Dem's book was part of the flood of Ancient Astronaut books inspired by the huge success of Erich von Daniken's Chariots of the Gods?