Gruber, Gary R. <br/><br/>
World`s 200 hardest  brain teasers: Mind boggling puzzles, problems, and curious questions to sharpen your brain 

 - Naperville  Sourcebooks 
 - 188p. 
<br/><br/><label>ISBN: </label>978-1-4022-3857-4 
<br/><br/><label>Dewey Class. No.: </label>793.73  G921B