by J. Ehlers <br/><br/>
Lecture Notes in Physics 
J.Ehles 
 - New York:  Springer-Verlag.  1971p. 
 - 179p. 
<br/><br/><label>ISBN: </label>35400554189 
<br/><br/><label>Dewey Class. No.: </label>513.2  / EHL/L