I've read this book and found his work to be poor. He cherry picks his information to support his hypothesis without looking at the whole picture and sources that disagree with him. His linguistic work is entirely unprofessional as he disregards time, location, natural rate of change, and language groups to support his idea of loan words transferring from one group to another. His claims are also extremely racist as they discount the feats and ability of natives in favor or promoting his own race. His whole book is also littered with logical fallacies and false claims from undocumented or personal sources.