SHERVATOV,V.G. <br/><br/>
Hyperbolic Functions: with configuration Theorems and Equivalent and Equidecomposable Figures 

 - New York  Dover  2007 
 - 68 
<br/><br/><label>ISBN: </label>9780486458861 
<br/><br/><label>Dewey Class. No.: </label>517.36  / SHE