don't know of any books, but i do use one i made (amethyst point), frequently, to find lost objects. first i connect with my spirit guides, and let the pendulum point the way. as far as which of the two directions to look in, i feel a subtle tug in the correct one. funny thing is, if i don't properly connect, it doesn't work until i do.
i also sometimes use it for simple "yes or no questions".