Einstein, Albert. <br/><br/>
The collected papers of albert einstein.  the berlin years :  correspondence, january 1919-april 1920 /  Volume  9 : 
Albert Einstein, Diana Kormos Buchwald, Robert Schulmann, Jozsef Illy, Daniel Kennefick, Tilman Sauer. 
 - [S.l.] :  Princeton University Press,  2004. 
 - 780 p. ;  26 cm. 
 - Original texts. .
 - Original texts. .
<br/><br/><label>ISBN: </label>0691120889 9780691120881 
<br/><br/><label>Dewey Class. No.: </label>530