Eberlein, Patrick <br/><br/>
Surfaces of Nonpositive Curvature   
by Patrick Eberlein 
 - Providence  American Mathematical Society  1979 
 - x,90p. 
 - Memoirs of the American Mathematical Society, vol 20, No.218 .
<br/><br/><label>ISBN: </label>0821822187 
<br/><br/><label>Dewey Class. No.: </label>516.362  / N79;1