Ballmann, Werner Gromov, Mikhael <br/><br/>
Manifolds of nonpositive curvature 

 - Boston  Birkhauser  1985 
 - iv,263 p .  22cm.  PB 
 - Progress in mathematics .
<br/><br/><label>ISBN: </label>081763181X 
<br/><br/><label>Subjects--Uniform Titles: </label><br/>Geometry
<br/><br/><label>Dewey Class. No.: </label>516  / BAL