You can say "these very books" or "this very book" but you have to say "this"/"these" and you cannot use "the" i.e. you cannot say *"the very book is". However, you can use it if it's followed by a relative clause. For example: "the very book that the authorities do not want you to read" E.g. I had been looking for the holy grail for so long. Little did I know it was located right within these very walls!

yes, yes