The Astronomical Almanac for the year 1981 
U.S.Government Printing Office                               
 - Washington  U. S. Government Printing Office  1980 
 - [various pagings.] 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Almanacs<br/>Astronomy and Astrophysics Thesaurus<br/>Ephemerides
<br/><br/><label>Universal Decimal Class. No.: </label>059:52  / AAL-81