Ehlers, J. (Ed.) MacGregor, Malcolm H. <br/><br/>
Lecture notes in physics- 81 

 - Berlin  Springer-Verlag  1978 
 - Bp. 
<br/><br/><label>ISBN: </label>3540088571 
<br/><br/><label>Dewey Class. No.: </label>530  / L39