KOPFF, A. <br/><br/>
The mathematical theory of relativity / 
[by] A.Kopff; translated H.Levy 
 - London  Methuen & Co.  1921 
 - 214 p. 
<br/><br/><label>ISBN: </label>71855 
<br/><br/><label>Dewey Class. No.: </label>530.11  / KOP