Other Tongues--Other Flesh
by George Hunt Williamson
Williamson has a somewhat opaque and very inflated resume. While his official bibliography lists numerous academic credentials and honors, Williamson actually dropped out of college, purchased some of his degrees from a diploma mill and invented the rest. He also claims to be an expert on Southwestern Native Americans, which is strange, because I've never seen any papers by him on that topic. Despite the attempt to reinvent himself as a bona fide scientist, Williamson repeatedly disparages the scientific method in this book, calling scientists 'The Guessers.'
Even murkier is his association with the Nazi William Dudley Pelley, whom he worked for briefly in the early 1950s. That said, it is difficult to spot any explicit trace of extreme right-wing politics in this book. Williamson believed that most of the aliens visiting Earth look like humans (or are humans), are benign, and preach a telepathic message of peace and brotherhood. In this book at least, the amoral, almond-eyed 'grey' aliens who conduct hostile abduction of humans for medical experimentation and mutilate livestock are nowhere to be found.
This book fell into the public domain in the US, because it was not renewed at the US copyright office in a timely fashion as required by law at the time. It is not currently in the public domain in any other country. For an independent report on the copyright registration and renewal status of this book, see this PDF file.