Books can be attributed to "Unknown" (no period) when the author or editor (as applicable) is not known and cannot be discovered. If at all possible, list at least one actual author or editor for a book instead of using "Unknown".
Books whose authorship is purposefully withheld should be attributed instead to Anonymous.
Very informative book about the intricate design of the human body, used as a bathroom reader. Probably won't remember even half of it. It amazes me that, though it shows the detailed design inherent in human biology, many or most scientists and doctors refuse to see it, belittle those who do, and glibly state that any design that is there is just an illusion. Oh my!