Conference on general relativity and cosmology (Villa monastero,1969) <br/><br/>
General relativity and cosmology   
ed. by B.K.Sachs 
 - New york  Academic Press  1971 
 - xi, 387p. 
 - International school of physics "ENRICO FERMI"  Course XLVII .
<br/><br/><label>Dewey Class. No.: </label>530.11  / N71