The Grolier Children's Encyclopedia  2 Black hole- Conservation 

 - Kingfisher Books Plc. ,London  Kingfisher Book Plc.  1998 
 - 95 
<br/><br/><label>ISBN: </label>0753403110 
<br/><br/><label>Dewey Class. No.: </label>RQ30J89g 1998 V .2