[2] Hidden Worlds: Fresh Clues to the Past is a rejection of Von Daniken's theories;[3][4][5] however, Der Veer and P.Moerman concede the existence of Atlantis.
[6][7] The book contests orthodox history, claiming international settlement in the Americas prior to European colonization of the region by Christopher Columbus in 1492.
[11] From P.Moerman, in 1977 a serious comprehensive and elaborate monography in Dutch appeared, by a completely different publisher, on his own personal field of interest paleoanthropology -in which he was generally respected as a self-educated expert in spite of lacking a formal academic background- specifically about the Neanderthals, "Op het spoor van de Neanderthalmens" ("On the tracks of Neanderthal Man").
That well-wrought monography had nothing in common with the sensational and speculative slant of the two previous books with Van der Veer, who was his brother-law.
This book about the Neanderthals was well received by scholars in the field and its content was clearly averse from the pseudo-scientific speculation thet was typical for "Hidden Worlds".