britannica book of the year 1981 
Encyclopedia Britannica 
 - Chicago  Encyclopaedia Britannica  1981 
 - 766p. 
<br/><br/><label>ISBN: </label>0-85227-381-X 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Astronomy and Astrophysics thesaurus<br/>Year Books-Encyclopaedia
<br/><br/><label>Universal Decimal Class. No.: </label>58.81  / BRI-81