Economicon by Al Smith 

You invite two people from the audience to assist. The two books, The Hidden Canvas and The Tenth Edition, are presented to the spectators, and the first spectator is asked to choose one of the two books. You hand the chosen book to the first spectator and hand the other book to the second spectator.
 
A third spectator is asked to think of a number between 1 and 100. Let’s say this third spectator’s name is “Tom”. You say, “Tom is thinking of a number. That number represents a page in your books. Please turn to that page.” Of course they can’t, because they don’t know the number. The natural and only solution is to have Tom announce his number. When the number is revealed, the first two spectators are asked to turn to that page in their books. Upon doing this, you reveal to both of them what the first word is at the top of the page in each of their books!
 
The included instructions contain additional routines and variations.

Book Dimensions: Approximately 5" x 8" (13cm x 20cm)