This is not a bad book by means, but any Fender book written by Mr. Bacon, always seems to have a reference to the 'tremolo' system invented by Leo Fender, and how he chose the name in error. I would imagine all those years ago, possibly before Tony Bacon was born, Leo came up with the name Tremolo, probably from the Italian word tremulant, Latin based,(read up on it, make your own mind up). The 'tremolo unit' can do a great deal for the accomplished user, and of course, produce a vibrato effect, as of course the human voice can.
That said, this a good read, well written, with excellent illustrations, and quite informative.