Assertion: keel's book | /r/HasProperty | ufo
Facets:
Source sentences:
text: His third book, UFOs: Operation Trojan Horse, published in 1970, linked UFOs to supernatural concepts such as monsters, ghosts and demons.
text: His third book, UFOs: Operation Trojan Horse, published in 1970, linked UFOs to supernatural concepts such as monsters, ghosts and demons.