Gons, David <br/><br/>
An introduction to non-Euclidean geometry / 
David Gans 
 - New York :  Academic Press,  1973 
 - 274 p. :  ill. ;  24 cm. 
<br/><br/> With answers to selected exercise 
<br/><br/>Includes bibliography and index. 
<br/><br/><label>ISBN: </label>0122748506 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Geometry, Non-Euclidean