Sommerville, D.M.Y. <br/><br/>
The elements of non-euclidean geometry/ 
by D.M.Y. Sommerville. 
 - New York:  Dover  c1958. 
 - xvi, 274 p. :  ill. ;  20 cm. 
<br/><br/>Includes index. 
<br/><br/><label>Dewey Class. No.: </label>516.9  / S697